Use UPDATE_HORIZON_CONFIG for manila_ui.overrides

Instead of manually editing local_settings.py, use the
UPDATE_HORIZON_CONFIG mechanism to set manila_ui overrides.
This simplifies the deployment process of the plugin.

Change-Id: I28b74892f6b400342b66cff8b599a29bf6cc6b56

README.rst

@@ -32,15 +32,6 @@ Set up your ``local_settings.py`` file::
 Open up the copied ``local_settings.py`` file in your preferred text
 editor. You will want to customize several settings:
 
--  ``HORIZON_CONFIG`` requires, an entry, ``customization_module``,
-   that refers to ``manila_ui.overrides``::
-
-    HORIZON_CONFIG = {
-        ...
-        'js_spec_files': [],
-        'customization_module': 'manila_ui.overrides',
-    }
-
 -  ``OPENSTACK_HOST`` should be configured with the hostname of your
    OpenStack server. Verify that the ``OPENSTACK_KEYSTONE_URL`` and
    ``OPENSTACK_KEYSTONE_DEFAULT_ROLE`` settings are correct for your

manila_ui/enabled/_90_manila_admin_shares.py

@@ -2,3 +2,6 @@ PANEL_DASHBOARD = 'admin'
 PANEL_GROUP = 'admin'
 PANEL = 'shares'
 ADD_PANEL = 'manila_ui.dashboards.admin.shares.panel.Shares'
+UPDATE_HORIZON_CONFIG = {
+    'customization_module': 'manila_ui.overrides',
+}

manila_ui/enabled/_90_manila_project_shares.py

@@ -4,3 +4,6 @@ PANEL = 'shares'
 ADD_PANEL = 'manila_ui.dashboards.project.shares.panel.Shares'
 # ADD_INSTALLED_APPS enables using html templates from within the plugin
 ADD_INSTALLED_APPS = ['manila_ui.dashboards.project']
+UPDATE_HORIZON_CONFIG = {
+    'customization_module': 'manila_ui.overrides',
+}

manila_ui/test/settings.py

@@ -73,7 +73,6 @@ HORIZON_CONFIG = {
                    'unauthorized': exceptions.UNAUTHORIZED},
     'angular_modules': [],
     'js_files': [],
-    'customization_module': 'manila_ui.overrides',
 }
 
 # Load the pluggable dashboard settings