gkeys: Ignore gkey.seeds file not found errors when installing new keys

Due to a keydir can have more than one key, it always tries to load an
existing gkey.seeds file.  This will let it ignore this error without reporting it to the screen.
It will still add a debug log message.
gkeys/seed.py: Add dictionary support to delete()

This allows the delete() to work with either a dictionary or GKEY input parameter.
gkeys/lib.py: add_key(),  Clean up some debug print()'s, improve debug messages
gkeys/cli.py: improve output_results() slightly
gkeys: Update seed file fetching to include the .sig's
gkeys: Add gpg verification to fetch_seeds()

Add gkey option to the seedurls config section to be used for verification of seeds.
SeedHandler, track successes better.