Added a context-button option to renderView

If your view has a special requirement for the context button then pass
through here.

The favourites collection is now managed by our app singleton.
Removed the favourite button for an empty context-button li
Removed Favourites from our main app launcher

This only needs to init the router and call history.start now.
Removed "editMode" from the FavouriteButtonView
No need to call the editMode
Added a specific context-button view for editing favourites
Render the manageFavourites route with a contextButtonView

Also removes any favourites code from the router initialize.
Merge pull request #37 from ox-it/context-button

Context button