feat(build runner): added in context, dockerfile_location

this is a new feature meant to allow people to use any file as
  a dockerfile and any folder as a context directory

buildtrigger/test/bitbucketmock.py

@@ -4,11 +4,11 @@ from mock import Mock
 from buildtrigger.bitbuckethandler import BitbucketBuildTrigger
 from util.morecollections import AttrDict
 
-def get_bitbucket_trigger(subdir=''):
+def get_bitbucket_trigger(dockerfile_path=''):
   trigger_obj = AttrDict(dict(auth_token='foobar', id='sometrigger'))
   trigger = BitbucketBuildTrigger(trigger_obj, {
     'build_source': 'foo/bar',
-    'subdir': subdir,
+    'dockerfile_path': dockerfile_path,
     'username': 'knownuser'
   })