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

endpoints/api/build.py

@@ -1,5 +1,5 @@
 """ Create, list, cancel and get status/logs of repository builds. """
-
+import os
 from urlparse import urlparse
 
 import logging
@@ -51,6 +51,7 @@ def user_view(user):
     'is_robot': user.robot,
   }
 
+
 def trigger_view(trigger, can_read=False, can_admin=False, for_build=False):
   if trigger and trigger.uuid:
     build_trigger = BuildTriggerHandler.get_handler(trigger)
@@ -133,6 +134,8 @@ def build_status_view(build_obj):
     'display_name': build_obj.display_name,
     'status': status or {},
     'subdirectory': job_config.get('build_subdir', ''),
+    'dockerfile_path': job_config.get('build_subdir', ''),
+    'context': job_config.get('context', ''),
     'tags': job_config.get('docker_tags', []),
     'manual_user': job_config.get('manual_user', None),
     'is_writer': can_write,
@@ -244,6 +247,7 @@ class RepositoryBuildList(RepositoryParamResource):
         raise InvalidRequest('Invalid Archive URL: Must be http or https')
 
     subdir = request_json['subdirectory'] if 'subdirectory' in request_json else ''
+    context = request_json['context'] if 'context' in request_json else os.path.dirname(subdir)
     tags = request_json.get('docker_tags', ['latest'])
     pull_robot_name = request_json.get('pull_robot', None)
 
@@ -291,9 +295,9 @@ class RepositoryBuildList(RepositoryParamResource):
     prepared.archive_url = archive_url
     prepared.tags = tags
     prepared.subdirectory = subdir
+    prepared.context = context
     prepared.is_manual = True
     prepared.metadata = {}
-
     try:
       build_request = start_build(repo, prepared, pull_robot_name=pull_robot_name)
     except MaximumBuildsQueuedException: