gkeys: Move most options to subparser selectable options

Use the original options, moved to individual functions in order that subparser actions can set which they need or support.
Replace the -s, --seeds and -r, --keydir options with a -c, --category otion.
Make the files option accept multiple args.
Make the -r, --keydir option solely for selecting sub-key keyrings.
gkeys/actions.py: Rename most keysdir variables and usage to catdir and args.category

There were too many keydir, keysdir and slight variations and was confusing.
gkeys: More variable renames in the config's and lib

More keysdir, keydir renames to clarify which is which.
gkeys: Add sign subcommand capability
gkeys/seedhandler.py: load_seeds() add doctring and filepath consistency
gkeys/utils.py: Correct file docstring
etc/gkeys.conf.sample: update config
gkeys/ations.py: Move ssl-fetch import to action function it is used

This reduces the import load to only be for the function it is used.
It also removes the import on a system that does not have all the dependencies installed.
gkeys/seedhandler.py: Move ssl-setch import to fetch_seeds

This removes the import for all but the fetch_seeds().
gkeys/action.py: Add multi file capability to sign action
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.
gkeys: Fix traceback for seed referenced before assignment
gkeys: Make the cli and Actions return True/Flase success

gkeys was not setting exit codes for operations.
All usable actions should now export success/fail and set the correct exit code.
gkeys/seed.py: Sort listseed results
gkeys/config.py: Prevent tracebacks for key not in the options or defaults