Reload HAProxy on refresh

Reload HAProxy on refresh

If the configuration for the HAProxy class or any of the frontend
endpoints has changed, we explicitly execute a reload on HA setups.
This is useful since on updates of HA setups we set pacemaker on
maintenance mode, and thus we are unable to refresh HAProxy's
configuration; The aforementioned detail is problematic, since some
puppet configurations rely on HAProxy taking into account the
configuration.  An example of this is changing a port in the endpoint
map or enabling SSL.

Change-Id: I7f26257fb43146afebca928f5498ee2174178063