added bestander for notifications of travis ci status changes

Summary:for tracking Travis stability
Closes https://github.com/facebook/react-native/pull/6277

Differential Revision: D3006229

fb-gh-sync-id: 31266cb3b73d57946cfd1518365f465642f0173a
shipit-source-id: 31266cb3b73d57946cfd1518365f465642f0173a

.travis.yml

@@ -52,3 +52,10 @@ branches:
   only:
     - master
     - /^.*-stable$/
+
+notifications:
+  email:
+    recipients:
+      - bestander@gmail.com
+    on_failure: change
+    on_success: change