repo: smarter _DetailedLibrepoError construction.
remove: support for gpgcakey gets dropped for now.

Its old implementation is convoluted and there is no indication anybody is
using it at the moment.
packaging: pygpgme is a requirement.

Without it the crypto functions are failing silently.

Related: RhBug:1118236
syntax: fixed indentation
transifex update
unicode: fixed locale.format error (RhBug:1130432)