Added cards from the initial reveal of Goblins vs Gnomes.
Merge remote-tracking branch 'origin/master'
Updated documentation and made agent naming more descriptive.

Documentation still needs an overview of the tag system, but it is at least
mentioned now.
Cleaned up the copying and serialization of hero objects.
Removed unneeded documentation.
Merge branch 'master' of https://github.com/danielyule/hearthbreaker into danielyule-master

Conflicts:
	hearthbreaker/game_objects.py

Merge.
Merge branch 'danielyule-master'