Fix text of some errors

Author: pyhedgehog

git_repo/services/service.py

@@ -78,7 +78,7 @@ def store_config(cls, config, **kwarg):
             section = 'gitrepo "{}"'.format(cls.name)
             for option, value in kwarg.items():
                 if option not in cls.config_options:
-                    raise ArgumentError('Option {} is invalid and cannot be setup.')
+                    raise ArgumentError('Option {} is invalid and cannot be setup.'.format(option))
                 config.set_value(section, option, value)
 
     @classmethod
@@ -120,7 +120,7 @@ def get_service(cls, repository, command):
             if 'type' not in config:
                 raise ValueError('Missing service type for custom service.')
             if config['type'] not in cls.service_map:
-                raise ValueError('Service type {} does not exists.')
+                raise ValueError('Service type {} does not exists.'.format(config['type']))
             service = cls.service_map.get(config['type'], cls)
 
         cls._current = service(repository, config)