Convert usage of Marshall to JSON (or another)

[amoeba]

So it turns out Marshaling clears method caches: https://github.com/haileys/charlie.bz/blob/master/posts/things-that-clear-rubys-method-cache.md#marshal-loading-an-extended-object. I use marshaling when caching to Redis. This is probably not affecting performance to a degree I'd care about but I did notice newrelic identifies a small portion of all requests result in method cache invalidation:

Since I only use Marshal every five minutes or so, the expected rate of method cache invalidations is about 10/(130605) = 0.0003 which is only an order of magnitude off of the above chart.