Allow to override local_setttings.py template

Add the ability to override the location of the template
used to generate local_setttings.py configuration file.

This could be useful in situations where the provided template
isn't flexible enough to allow the configuration of some settings.

The value still defaults to 'horizon/local_settings.py.erb'.

Change-Id: I8dca1324324b5c96487b9e900b1fe89a38943dcd
Redirect horizon URL on Debian like on Red Hat

Change-Id: I8b7de7e21e5ae8c970252ad51008c0d8ee714e0e
Merge branch 'dev' of https://github.com/gwdg/puppetlabs-horizon into dev