Add tab for genre display and management

[JavLuv]

Add a "Genres" tab. From here, user will be able to:

• See genres in alphabetical or popularity (count)
• Set new genre filters (delete or transform)
• Double-click or select to view all movies of this genre

Possible design idea: Split page into an upper browser containing sorted (by name or count) list of all genres. Lower half would be list of movies containing selected genres. Potential complications for this design are that two different sorting dropdowns will be needed in the sidebar, one for the genres and one for the selected movies.

Hopefully won't be too awkward to implement. Currently seems like the most flexible design though. Will also need a filter option to filter only genres - I think this shouldn't be too hard with existing code design.