Horizon: Fix and reload missing css in Pike

Horizon: Fix and reload missing css in Pike

The horizon in Pike release is broken due to missing
the static content. This workaround is to:

- create a missing symbolic link.
  The link is defined as an alias in the apache configuraion
- collecting and compressing static assets
- add single "Default" theme as AVAILABLE_THEMES
- restart apache2 service
- apply the workaround to Salt states
 'openstack_ha' and 'openstack_noha'

JIRA: FUEL-324

Change-Id: Idd70165f1be8d31967a3ab518323e6f3e8406624
Signed-off-by: ting wu <ting.wu@enea.com>