##### SUMMARY
The documentation mentions the ability to specify a galaxy server parameter via the syntax `ANSIBLE_GALAXY_SERVER_{{ id }}_{{ key }}`, but this seems to not be working for the URL of an example of this.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/cli/galaxy.py

##### ANSIBLE VERSION
```
ansible --version
ansible 2.9.0.dev0
  config file = None
  configured module search path = ['/Users/alancoding/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/alancoding/Documents/repos/ansible/lib/ansible
  executable location = /Users/alancoding/.virtualenvs/ansible3/bin/ansible
  python version = 3.6.5 (default, Apr 25 2018, 14:23:58) [GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)]
```

##### CONFIGURATION
```
ANSIBLE_NOCOWS(env: ANSIBLE_NOCOWS) = True
```

##### OS / ENVIRONMENT
Mac OS, control machine, also on CentOS


##### STEPS TO REPRODUCE
Run this command

```yaml
ANSIBLE_GALAXY_SERVER_GALAXY_URL=https://galaxy.ansible.com ANSIBLE_GALAXY_SERVER_PRIVATE_GALAXY_URL=https://galaxy-dev.ansible.com ANSIBLE_GALAXY_SERVER_LIST=private_galaxy,galaxy ansible-galaxy collection install -r fallback_not_found/collections/requirements.yml -p dest -vvvv
```

where the content is

```
cat fallback_not_found/collections/requirements.yml
collections:
  - name: "chrismeyersfsu.test_things"
  - name: "chrismeyersfsu.tower_modules"
```

##### EXPECTED RESULTS
I expect it to attempt to install from the development galaxy server, and then get a 404, and then install from the release galaxy server.

This works if I do not use these environment variables and instead use the config:

```
[galaxy]
server_list = dev_galaxy,galaxy

[galaxy_server.dev_galaxy]
url=https://galaxy-dev.ansible.com

[galaxy_server.galaxy]
url=https://galaxy.ansible.com/
```

The documentation describes this use case here:

https://github.com/jborean93/ansible/blob/devel/docs/docsite/rst/dev_guide/collections_tech_preview.rst

> As well as being defined in the ansible.cfg file, these server options can be defined as an environment variable. The environment variable is in the form ANSIBLE_GALAXY_SERVER_{{ id }}_{{ key }} where {{ id }} is the upper case form of the server identifier and {{ key }} is the key to define. For example I can define token for release_galaxy by setting ANSIBLE_GALAXY_SERVER_RELEASE_GALAXY_TOKEN=secret_token.

The setting for the host is `url`

> url: The URL of the galaxy instance to connect to, this is required.

##### ACTUAL RESULTS
```
ansible-galaxy 2.9.0.dev0
  config file = None
  configured module search path = ['/Users/alancoding/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/alancoding/Documents/repos/ansible/lib/ansible
  executable location = /Users/alancoding/.virtualenvs/ansible3/bin/ansible-galaxy
  python version = 3.6.5 (default, Apr 25 2018, 14:23:58) [GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)]
No config file found; using defaults
ERROR! No setting was provided for required configuration plugin_type: galaxy_server plugin: private_galaxy setting: url 
```

I also tried removing "galaxy" from the names, and this has the same result.

```
ANSIBLE_GALAXY_SERVER_FOO_URL=https://galaxy.ansible.com ANSIBLE_GALAXY_SERVER_BAR_URL=https://galaxy-dev.ansible.com ANSIBLE_GALAXY_SERVER_LIST=bar,foo ansible-galaxy collection install -r fallback_not_found/collections/requirements.yml -p dest -vvvv
ansible-galaxy 2.9.0.dev0
  config file = None
  configured module search path = ['/Users/alancoding/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/alancoding/Documents/repos/ansible/lib/ansible
  executable location = /Users/alancoding/.virtualenvs/ansible3/bin/ansible-galaxy
  python version = 3.6.5 (default, Apr 25 2018, 14:23:58) [GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)]
No config file found; using defaults
ERROR! No setting was provided for required configuration plugin_type: galaxy_server plugin: bar setting: url 
```

Ping @jborean93 @chrismeyersfsu @ryanpetrello 

We do _not_ rate this as a Tower blocker, because the `ansible.cfg` specification of parameters is known to work, and we will begin to design around that.
"""
        prints out detailed information about an installed role as well as info available from the galaxy API.
        """
        roles_path = context.CLIARGS['roles_path']
        data = ''
        for role in context.CLIARGS['args']:
            role_info = {'path': roles_path}
            gr = GalaxyRole(self.galaxy, role)
            install_info = gr.install_info
            if install_info:
                if 'version' in install_info:
                    install_info['installed_version'] = install_info['version']
                    del install_info['version']
                role_info.update(install_info)
            remote_data = False
            if not context.CLIARGS['offline']:
                remote_data = self.api.lookup_role_by_name(role, False)
            if remote_data:
                role_info.update(remote_data)
            if gr.metadata:
                role_info.update(gr.metadata)
            req = RoleRequirement()
            role_spec = req.role_yaml_parse({'role': role})
            if role_spec:
                role_info.update(role_spec)