allow -c abbrv for --config

sloth/core/cli.py

@@ -84,7 +84,7 @@ class BaseCommand(object):
         make_option('-v', '--verbosity', action='store', dest='verbosity', default='1',
             type='choice', choices=['0', '1', '2', '3'],
             help='Verbosity level; 0=minimal output, 1=normal output, 2=all output'),
-        make_option('--config',
+        make_option('-c', '--config',
             help='The Python path to a configuration file, e.g. "myconfig". If this isn\'t provided, sloth\'s default configuration will be used.'),
         make_option('--pythonpath',
             help='A directory to add to the Python path, e.g. "/home/user/labeling".'),