Add special case for Ghostfire in controllers.process_card

Ghostfire is colorless even though the parser will think it is red
(mana cost is 2R)
Add shell of "GathererDownloader" converter

This script takes the raw values from GathererDownloader and adds
rich comparison values such as integer power, toughness, as well as
new fields such as tilde rules (for finding self-referential cards) or
ascii name for the whole series of Aether <Whatever>.

Currently this only sets up reading, and does not properly open a file
for writing.