Prepare 3.0.0 release (#318)

* Prepare 3.0.0 release.

* Install using ansible-galaxy via git instead of cloning directly.

plugins/modules/command.py

@@ -20,16 +20,14 @@ description:
   - The module always indicates a (changed) status. You can use
     R(the changed_when task property,override_the_changed_result) to determine
     whether a command task actually resulted in a change or not.
-notes:
-  - The module declares that it B(supports check mode). This is a bug and will
-    be changed in community.routeros 3.0.0.
 extends_documentation_fragment:
   - community.routeros.attributes
 attributes:
   check_mode:
-    support: partial
+    support: none
     details:
-      - The module claims to support check mode, but it simply always executes the command.
+      - Before community.routeros 3.0.0, the module claimed to support check mode.
+        It simply executed the command in check mode.
   diff_mode:
     support: none
   platform:
@@ -165,7 +163,7 @@ def main():
     argument_spec.update(routeros_argument_spec)
 
     module = AnsibleModule(argument_spec=argument_spec,
-                           supports_check_mode=True)
+                           supports_check_mode=False)
 
     result = {'changed': False}