Add screenshots to e2e test

Author: tinayuangao

tools/gulp/tasks/e2e.ts

@@ -64,6 +64,7 @@ task('e2e', (done: (err?: string) => void) => {
     'serve:e2eapp',
     ':test:protractor',
     ':serve:e2eapp:stop',
+    'screenshots',
     (err: any) => done(err)
   );
 });

tools/gulp/tasks/screenshots.ts

@@ -22,6 +22,7 @@ task('screenshots', () => {
       .then((results: boolean) => {
         return database.ref(FIREBASE_REPORT).child(`${prNumber}/result`).set(results);
       })
+      .then(() => database.ref(FIREBASE_REPORT).child(`${prNumber}/commit`).set(process.env['TRAVIS_COMMIT']))
       .then(() => setFilenameList(database, prNumber))
       .then(() => uploadScreenshots(prNumber, 'diff'))
       .then(() => uploadScreenshots(prNumber, 'test'))