move environment variable gathering to end of __init__() (#3890)

* This moves the lines in the code that parse the `env` and `env_file` options for docker to the end of the `__init__()` function.
This is needed because the `_check_capabilites` function needs both a working `self.client` and a proper `self.docker_py_versioninfo`.
`_check_capabilities` is used by `ensure_capabilities` which is, in turn, used by `get_environment`

This means that before this commit, the environment variables could not be loaded because both `self.client` and `self.docker_py_versioninfo` were not set at that time.

This commit fixes that by putting the environment variable parsing after those two.

* This moves the lines in the code that parse the `env` and `env_file` options for docker to the end of the `__init__()` function.
This is needed because the `_check_capabilites` function needs both a working `self.client` and a proper `self.docker_py_versioninfo`.
`_check_capabilities` is used by `ensure_capabilities` which is, in turn, used by `get_environment`

This means that before this commit, the environment variables could not be loaded because both `self.client` and `self.docker_py_versioninfo` were not set at that time.

This commit fixes that by putting the environment variable parsing after those two.

cloud/docker/_docker.py

@@ -745,10 +745,6 @@ class DockerManager(object):
         if self.module.params.get('links'):
             self.links = self.get_links(self.module.params.get('links'))
 
-        env = self.module.params.get('env', None)
-        env_file = self.module.params.get('env_file', None)
-        self.environment = self.get_environment(env, env_file)
-
         self.ulimits = None
         if self.module.params.get('ulimits'):
             self.ulimits = []
@@ -847,6 +843,10 @@ class DockerManager(object):
 
         self.docker_py_versioninfo = get_docker_py_versioninfo()
 
+        env = self.module.params.get('env', None)
+        env_file = self.module.params.get('env_file', None)
+        self.environment = self.get_environment(env, env_file)
+
     def _check_capabilities(self):
         """
         Create a list of available capabilities