core: add 3.5 support

This patch adds 3.5 support in code, tests and DB configuration
It also creates default 3.5 DC and Cluster and enables to create
new 3.5 DCs and Clusters

Change-Id: Icb0c3ce202789d983cae95b0b1ea4ef0ead73e0d
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1095258
Signed-off-by: Eli Mesika <emesika@redhat.com>