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

tools/migratebranchregex.py

@@ -5,6 +5,7 @@ import json
 from app import app
 from data import model
 from data.database import RepositoryBuildTrigger, configure
+from data.model.build import update_build_trigger
 
 configure(app.config)
 
@@ -40,8 +41,7 @@ def run_branchregex_migration():
       config['branchtag_regex'] = new_regex
 
       logger.debug("Updating to branchtag regex '%s'", new_regex)
-      trigger.config = json.dumps(config)
-      trigger.save()
+      update_build_trigger(trigger, config)
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG)