##### SUMMARY
`ansible-galaxy collection install` currently requires the user to specify an install path using the `-p` option. Galaxy currently generates and displays the CLI command for installing a collection. There is no way for Galaxy to determine a value for `-p`, and hard coding a default value into Galaxy makes no sense.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
`ansible-galaxy`

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```
ansible 2.10.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/Users/chouseknecht/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/chouseknecht/projects/ansible/lib/ansible
  executable location = /Users/chouseknecht/.pyenv/versions/venv27/bin/ansible
  python version = 2.7.14 (default, Nov 14 2017, 23:24:24) [GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.38)]
```

raise AnsibleError("Expecting requirements file to be a dict with the key 'collections' that contains "
                                   "a list of collections to install")
            for role_req in file_requirements:
                requirements['roles'] += parse_role_req(role_req)
        else:
            
            extra_keys = set(file_requirements.keys()).difference(set(['roles', 'collections']))
            if extra_keys:
                raise AnsibleError("Expecting only 'roles' and/or 'collections' as base keys in the requirements "
                                   "file. Found: %s" % (to_native(", ".join(extra_keys))))
            for role_req in file_requirements.get('roles', []):
                requirements['roles'] += parse_role_req(role_req)
            for collection_req in file_requirements.get('collections', []):
                if isinstance(collection_req, dict):
                    req_name = collection_req.get('name', None)
                    if req_name is None:
                        raise AnsibleError("Collections requirement entry should contain the key name.")
                    req_version = collection_req.get('version', '*')
                    req_source = collection_req.get('source', None)
                    if req_source:
                        
                        
                        req_source = next(iter([a for a in self.api_servers if req_source in [a.name, a.api_server]]),
                                          GalaxyAPI(self.galaxy, "explicit_requirement_%s" % req_name, req_source))
                    requirements['collections'].append((req_name, req_version, req_source))
                else:
                    requirements['collections'].append((collection_req, '*', None))
        return requirements
    @staticmethod
    def exit_without_ignore(rc=1):