Add methods for getting full release string and release number

Signed-off-by: Tomas Hozza <thozza@redhat.com>
Add method for setting release number

Signed-off-by: Tomas Hozza <thozza@redhat.com>
Add methods for redefining Release with macro, and revert method

Signed-off-by: Tomas Hozza <thozza@redhat.com>