gkeys/cli.py: Fix --category option variable name
gkeys/actions.py: Debug addseed(), removeseed()

Remove unused searchkey in removeseed.
Add check for a returned gkey before adding nothing to the seed file.
gkeys: Add multiple fingerprint option in the cli and supporting actions, libs

SeedHandler:
    Modify to properly handle multiple fingerprints.
    Debug the check_key function, only return a new GKEY instance if the checks passed.
    Fix a filepath, config assignment.

Seeds:
    Fix list() to handle string fileds comparisons correctly.
    Fix _seeds2json() to return and empty dictionary for empty seeds.
    This prevents a traceback and allows saving an empty list.  
    Usefull if the last seed is removed from an existing file.