Add ArtistService function

- Replaces ArtistObject variable
- Acts as a service function interacting between search and favorites controllers
Add band container add button stub in html template

- Empty button is loaded with page
- Use for favorites add event listener
Add Shogogo namespace to FavoritesView

- Update reference in BandView
- Edit function name in FavoritesView.js
Refactor favorite artist event listener

- Remove from initialize.js
- Add addFavoriteListener method in FavoritesController
- Add addFavorite method in FavoritesController to post favorite to server