trigger: pass trigger into manual_start & handle_trigger_request

buildman/component/buildcomponent.py

@@ -131,6 +131,9 @@ class BuildComponent(BaseComponent):
 
     # If the trigger has a private key, it's using git, thus we should add
     # git data to the build args.
+    #  url: url used to clone the git repository
+    #  sha: the sha1 identifier of the commit to check out
+    #  private_key: the key used to get read access to the git repository
     if build_job.repo_build.trigger.private_key is not None:
       build_arguments['git'] = {
         'url': build_config['trigger_metadata']['git_url'],