<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
docker_container is not idempotent when specifying an ip address

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
docker_container

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.5
  config file = /home/pkueck/projects/cix.de/cix-ansible/ansible.cfg
  configured module search path = ['/home/xxx/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.4 (default, Jul  9 2019, 16:32:37) [GCC 9.1.1 20190503 (Red Hat 9.1.1-1)]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
n/a
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Fedora 30, CentOS 7

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
---
- hosts: myhost
  gather_facts: no
  tasks:
    - docker_network:
        name: "foonet"
        ipam_config:
          - subnet: 172.16.44.0/24
    - docker_container:
        name: "foo"
        state: present
        image: centos
        networks:
          - name: foonet
            ipv4_address: "172.16.44.11"
        networks_cli_compatible: yes
      loop: [1,2]
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
container created on first loop cycle, not touched on second one

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below
PLAY [myhost] ***************

TASK [docker_network] *******
ok: [myhost]

TASK [docker_container] *****
--- before
+++ after
@@ -1,9 +1,10 @@
 {
-    "exists": false,
+    "exists": true,
     "network.foonet": {
         "aliases": null,
-        "ipv4_address": "",
-        "ipv6_address": "",
+        "id": "27e539c3b9af0160f02a0532ad081d1bd1ef3dd93e652095ec96d6dfd95bf2fb",
+        "ipv4_address": "172.16.44.11",
+        "ipv6_address": null,
         "links": null,
         "name": "foonet"
     }

changed: [myhost] => (item=1)
--- before
+++ after
@@ -1,10 +1,9 @@
 {
     "network.foonet": {
-        "aliases": [
-            "44cfded131d7"
-        ],
-        "ipv4_address": "",
-        "ipv6_address": "",
+        "aliases": null,
+        "id": "27e539c3b9af0160f02a0532ad081d1bd1ef3dd93e652095ec96d6dfd95bf2fb",
+        "ipv4_address": "172.16.44.11",
+        "ipv6_address": null,
         "links": null,
         "name": "foonet"
     }

changed: [myhost] => (item=2)
```

memory_swap=host_config.get('MemorySwap'),
            ))
        differences = DifferenceTracker()
        for key, value in config_mapping.items():
            minimal_version = self.parameters.client.option_minimal_versions.get(key, {})
            if not minimal_version.get('supported', True):
                continue
            compare = self.parameters.client.comparisons[self.parameters_map.get(key, key)]
            self.log('check differences %s %s vs %s (%s)' % (key, getattr(self.parameters, key), str(value), compare))
            if getattr(self.parameters, key, None) is not None:
                match = self._compare(getattr(self.parameters, key), value, compare)
                if not match:
                    
                    p = getattr(self.parameters, key)
                    c = value
                    if compare['type'] == 'set':
                        
                        if p is not None:
                            p = sorted(p)
                        if c is not None:
                            c = sorted(c)
                    elif compare['type'] == 'set(dict)':
                        
                        if key == 'expected_mounts':
                            
                            def sort_key_fn(x):
                                return x['target']
                        else:
                            
                            def sort_key_fn(x):