ENH add --config argument
TST check passing arg overrides default/config
API use --global-config and --ignore-local-config arguments
Use lowercase
FIX autocomplete for --global-config arg and with space sep
CLN parse args twice, no manual arguments checking
CLN remove pragma: no cover as not needed with coveralls cc @myint
CLN remove _main
Merge remote-tracking branch 'hayd/config' into config
Revert 1f782659f13adf63969fb3d41bdbdf6cb56d148a

That commit removed things that were unrelated.
Remove unnecessary method
Format
Document new options
Use non-deprecated import
Handle more errors
Set development version
Add missing usage of "GLOBAL_CONFIG"

Also add fix-me note about non-safe code.
Add back Python 2.6 support
Clean up