Add $ngStorageChanged event after apply with changes

[schmuli]

If we detect changes during the apply phase, we broadcast a $ngStorageChanged event on the $rootScope.

Additionally, since we also detect any changes to the underlying storage and apply those in the same manner, this event will be broadcast when the change might have come from a different tab.

Fixes #214

[schmuli]

Sorry about the formatting in the test, my VI isn't setup correctly for JS.

Also, currently I only implemented one event which will be fired for both storage services, local and session. It should be trivial to add an indicator as part of the event data from which service the event was broadcast.

[dr3am3r]

any update on this?

[egilkh]

Seems like a good addition. Will merge.

[schmuli]

@egilkh Any chance of getting this merged any time soon?

Thanks.