fix(bower): increment angular version

This commit increments the angular version to resolve conflicts in
external dependencies.

bower.json

@@ -42,6 +42,6 @@
   },
   "resolutions": {
     "Chart.js": "~2.0.0",
-    "angular": "1.5.6"
+    "angular": "1.5.7"
   }
 }