Add trigger capability on github pr review

A github pull request review is a new type of event that happens when
user provides a review of a pull request
https://developer.github.com/v3/pulls/reviews

It will create an event
https://developer.github.com/v3/activity/events/types/#pullrequestreviewevent
sent to the webhook. Allow filtering on submitted or dismissed actions
and the state of the review of approved, comment, or request_changes.

Signed-off-by: Jesse Keating <omgjlk@us.ibm.com>
Change-Id: If94c2fe8adbe18fa7f426d5462559ba24963424c
diff --git a/tests/fixtures/layouts/reviews-github.yaml b/tests/fixtures/layouts/reviews-github.yaml
new file mode 100644
index 0000000..1cc887a
--- /dev/null
+++ b/tests/fixtures/layouts/reviews-github.yaml
@@ -0,0 +1,21 @@
+- pipeline:
+    name: reviews
+    manager: independent
+    trigger:
+      github:
+        - event: pull_request_review
+          action: submitted
+          state: 'approve'
+    success:
+      github:
+        label:
+          - 'tests passed'
+
+- job:
+    name: project-reviews
+
+- project:
+    name: org/project
+    reviews:
+      jobs:
+        - project-reviews