Add support for encrypting settings that are passwords.

awx/conf/conf.py

@@ -81,6 +81,9 @@ register(
     # Optional; licensed feature required to be able to view or modify this
     # setting.
     feature_required='rebranding',
+    # Optional; field is stored encrypted in the database and only $encrypted$
+    # is returned via the API.
+    encrypted=True,
 )
 
 register(