Amazon List is incomplete

[JRJurman]

The Problem

It appears there's a great deal of anime not being shown from amazon because it is not included with prime (but still available to rent or buy).

Navigating to the url shows only (at the time of writing)
148 shows / movies at Prime Video : Anime : Prime Eligible : Movies or TV Shows

However, if we set it to
Prime Video : Anime : Rent or Buy there are another 1000 available!

The Fix

I believe the AmazonPrime source in animesources.py needs to be duplicated, with the rent or buy link instead of the free with prime link.
https://www.amazon.com/s/ref=sr_pg_1?fst=as%3Aoff&rh=n%3A2858778011%2Cp_n_theme_browse-bin%3A2650364011%2Cp_n_ways_to_watch%3A12007867011&bbn=2858778011&ie=UTF8&qid=1527288121

Both need to be included to be inclusive of the free and purchasable anime (and not include anime that is no longer available).

[JRJurman]

I would make a PR but am unable to run the application locally, see #55