Switch default Git auth backend to the 'pagure_authorized_keys' backend
The Gitolite backend has turned into a rather difficult backend to support
by default. Among other things, newer versions of Gitolite seem to have
issues with parsing the configuration data generated by Pagure.
Combined with the performance issues for larger setups and the complexity
required to set up Pagure correctly with the Gitolite backend, it makes
sense to switch the default backend to the simpler, internal one.
Signed-off-by: Neal Gompa <email@example.com>