WIP: Add Imazon support

Adds Imazon support [here](https://github.com/wri/gfw-api/blob/feature/imazon/gfw/imazon.py). @andrewxhill can you double check [my Imazon queries](https://github.com/wri/gfw-api/blob/feature/imazon/gfw/imazon.py#L24-L40), totally winging it here ha. :)

Imazon defor values from 2005 to 2006:
http://gfw-apis.appspot.com/api/v1/defor/analyze/imazon/2005-03-05/2006-08-01

Here's the same query but analyzed within a GeoJSON polygon: [boom](http://gfw-apis.appspot.com/api/v1/defor/analyze/imazon/2005-03-05/2006-08-01?q={%20%22type%22:%20%22Polygon%22,%20%22coordinates%22:%20[%20[%20[%20-58.97460937499999,%200.08789059053083693%20],%20[%20-64.6875,%20-6.664607562172573%20],%20[%20-55.8984375,%20-15.961329081596634%20],%20[%20-48.69140625,%20-4.915832801313164%20],%20[%20-58.97460937499999,%200.08789059053083693%20]%20]%20]%20})

cc: @matallo