fix(grunt): update rev-ed images in css as well as js

closes #977

Author: Awk34

Diff for: app/templates/Gruntfile(grunt).js

@@ -311,6 +311,9 @@ module.exports = function (grunt) {
         ],
         // This is so we update image references in our ng-templates
         patterns: {
+          css: [
+            [/(assets\/images\/.*?\.(?:gif|jpeg|jpg|png|webp|svg))/gm, 'Update the CSS to reference our revved images']
+          ],
           js: [
             [/(assets\/images\/.*?\.(?:gif|jpeg|jpg|png|webp|svg))/gm, 'Update the JS to reference our revved images']
           ]