Do not override defaults in local_settings

By default, the puppet-horizon module sets some additional
variables in /etc/openstack-dashboard/local_settings that conflict
with the default values in the package version. Specifically:

COMPRESS_OFFLINE = True
FILE_UPLOAD_TEMP_DIR = '/tmp'

This patch fixes that and sets COMPRESS_OFFLINE to False and
FILE_UPLOAD_TEMP_DIR to /var/tmp. Please note it requires patch
https://review.openstack.org/133929 to puppet-horizon to work.

Change-Id: I48a838a04619efbbf8187e2d3cd22246f5ba29b6
Fixes: bz#1148770
Merge "Do not override defaults in local_settings"