Controller separation/revision, $emit event upon files selected

- Removed "StorageCtrl" `controller` from `dcv-storage-selector.js` and created `ctr-storage-selector.js` to separate into own file
- controller now handles listening for window "message" event and based on the `event.data`
- in window "message" event handler, if `event.data` is an Array, then `close()` is called on the `$modalInstance` passing the value of `event.data`
- gulp file and e2e test HTML file updated for inclusion of the new controller file