Add lint to Travis.

.travis.yml

@@ -19,6 +19,7 @@ install:
       export AWS_ACCESS_KEY_ID=foobar_key
     fi
 script:
+  - make lint
   - make test
 after_success:
   - coveralls

moto/core/models.py

@@ -211,6 +211,8 @@ class Model(type):
 
 
 model_data = defaultdict(dict)
+
+
 class InstanceTrackerMeta(type):
     def __new__(meta, name, bases, dct):
         cls = super(InstanceTrackerMeta, meta).__new__(meta, name, bases, dct)
@@ -223,6 +225,7 @@ class InstanceTrackerMeta(type):
         cls.instances = []
         return cls
 
+
 @six.add_metaclass(InstanceTrackerMeta)
 class BaseModel(object):
     def __new__(cls, *args, **kwargs):