bash-completion: fix local comletion (RhBug: 1151231)

we will use dnf python api

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1151231
Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
bash-completion: more performance with caching

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>