Make fedora-packager-kerberos subpackage
Breaks out the kerberos configs into own subpackage so that users
who want to connect to kerberos but not install all the depenencies
of `fedora-packager` can do that.
Fixes https://pagure.io/fedora-packager/issue/152
Signed-off-by: Dusty Mabe <dusty@dustymabe.com>