Merge pull request #572 from dlorenc/master

Change decorators to use a relative import.

Author: shin-

docker/utils/decorators.py

@@ -1,12 +1,12 @@
-import docker.errors
+from .. import errors
 
 
 def check_resource(f):
     def wrapped(self, resource_id=None, *args, **kwargs):
         if resource_id is None and (
             kwargs.get('container') is None and kwargs.get('image') is None
         ):
-            raise docker.errors.NullResource(
+            raise errors.NullResource(
                 'image or container param is None'
             )
         return f(self, resource_id, *args, **kwargs)