Allow Horizon Custom Branding

This introduces 2 variables:
``horizon_site_name`` and ``horizon_custom_uploads``.

The former needs to set with a string. It will edit the
local settings of horizon to add the cloud's name.

The latter is a dict, that contains path to source and destination
files that the deployer wants to upload.
For example, if setting the dict as followed:

horizon_custom_uploads:
  logo:
    src: '/etc/openstack_deploy/files/logo.png'
    dest: "img/logo.png"
  logosplash:
    src: '/etc/openstack_deploy/files/logo-splash.png'
    dest: "img/logo-splash.png"

You'll overwrite the img/logo.png and img/logo-splash.png files
on the horizon nodes (inside their folder
"{{ horizon_lib_dir }}/openstack_dashboard/static/dashboard/")
with the files stored on the deployment node at the src location.

Change-Id: I1a74e74968d09f6e299dbd965f9c87368c4d646c

tasks/horizon_post_install.yml

@@ -45,6 +45,16 @@
   notify: Restart apache2
   tags:
     - horizon-configs
+    - horizon-branding
+
+- name: Uploading horizon custom files
+  copy:
+    src: "{{ item.value.src }}"
+    dest: "{{ horizon_lib_dir }}/openstack_dashboard/static/dashboard/{{ item.value.dest }}"
+  with_dict: "{{ horizon_custom_uploads | default({}) }}"
+  when: horizon_custom_uploads is defined
+  tags:
+    - horizon-branding
 
 - name: Create horizon links
   file:

templates/horizon_local_settings.py.j2

@@ -710,3 +710,7 @@ REST_API_REQUIRED_SETTINGS = ['OPENSTACK_HYPERVISOR_FEATURES']
 # For more information see:
 # http://tinyurl.com/anticlickjack
 #DISALLOW_IFRAME_EMBED = True
+
+{% if horizon_site_name is defined %}
+SITE_BRANDING = '{{ horizon_site_name }}'
+{% endif %}