fix(bower): add extra config to ensure bower works in app folder

If you ran `bower install` from the app folder then bower was installing
the wrong versions of components into the wrong folders.  This should
correct that.

Closes angular/angular.js#7508

app/.bowerrc

@@ -0,0 +1,4 @@
+{
+  "cwd": "..",
+  "directory": "app/bower_components"
+}