Moved attract.shots to attract.shots_and_assets

Assets are going to be pretty much the same thing as shots, with a few
different properties. Hooks and much other code can be reused.

tests/test_shots.py

@@ -407,7 +407,7 @@ class RequiredAfterCreationTest(AbstractShotTest):
 class ProjectSummaryTest(unittest.TestCase):
 
     def setUp(self):
-        from attract.shots import ProjectSummary
+        from attract.shots_and_assets import ProjectSummary
 
         self.summ = ProjectSummary()
         self.summ.count(u'todo')