Chrisrw/small refactors

@pbouzakis I've made another small pull request here.  This is an update to have helper getter/finder functions at your suggestion.  The data service is now utilizing underscore.

To note: I found I had to pass in the storedCds or storedArtists object into the finder functions in order to get the  reference to the exact object - maybe you can help me update this if you think it's needed.

Otherwise I feel good about theses updates, thanks!