YAMLLintBear.py: Correct argument "--config"

Corrected the argument at line 53 from ``--config`` to ``--config-file``

Fixes coala#979

bears/yml/YAMLLintBear.py

@@ -50,7 +50,7 @@ def create_arguments(filename, file, config_file, yamllint_config: str=''):
         """
         args = ('-f', 'parsable', filename)
         if yamllint_config:
-            args += ('--config=' + yamllint_config,)
+            args += ('--config-file=' + yamllint_config,)
         else:
             args += ('--config-file=' + config_file,)
         return args