core: Add Debian 7 to the list of operating systems

Added entry for Debian 7 in osinfo (deriving from Ubuntu)
and two icons for userportal.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1073453
Change-Id: I2f41e8ea651d900b89944c791f25e7d99d2de5e8
Signed-off-by: Martin Betak <mbetak@redhat.com>