presets: Add presets module

Previously some branding specific values resided everywhere in the
codebase. The presets module shall help to ease the branding of several
user visible parts.

Change-Id: I1af33147179ac3bbce938ae618b7067d97013c72
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=922915
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>