Address some pylint issues (#1155)

* Address cyclic-import.

* Address redefined-builtin.

* Address redefined-argument-from-local.

* Address many redefined-outer-name.

* Address pointless-string-statement.

* No longer needed due to separate bugfix.

* Address useless-return.

* Address possibly-used-before-assignment.

* Add TODOs.

* Address super-init-not-called.

* Address function-redefined.

* Address unspecified-encoding.

* Clean up more imports.

plugins/inventory/docker_machine.py

@@ -170,15 +170,15 @@ class InventoryModule(BaseInventoryPlugin, Constructable, Cacheable):
 
         # capture any of the DOCKER_xxx variables that were output and create Ansible host vars
         # with the same name and value but with a dm_ name prefix.
-        vars = []
+        env_vars = []
         for line in env_lines:
             match = re.search('(DOCKER_[^=]+)="([^"]+)"', line)
             if match:
                 env_var_name = match.group(1)
                 env_var_value = match.group(2)
-                vars.append((env_var_name, env_var_value))
+                env_vars.append((env_var_name, env_var_value))
 
-        return vars
+        return env_vars
 
     def _get_machine_names(self):
         # Filter out machines that are not in the Running state as we probably cannot do anything useful actions