Make popular media more dynamic

This PR:

* Creates a `media_views` table to track the number of views and dates of each view
* Adds a `popular_play_count` column in addition to `play_count` to the `media` table. 
* `popular_play_count` will track the number of views in the last month
* Adds a script to maintain the `media_views` table `popular_play_count` column via cron
* Replaces the latest media band with popular media
* Uses the `popular_play_count` when sorting by popular (should provide a more up-to-date and dynamic experience)
* Removes old popular code

No, I meant to get rid of it, but I should create a fresh $options variable instead.

I didn't see how it would be useful to allow query parameters to adjust the display of the 'popular' media on the homepage.