Added tests based on parsed card tests.

Fixed some cards that weren't implemented correctly.
Implemented Explosive Trap
flake8 fixes
Update cards.csv
Fixed bug with Tirion.

If Tirion died on the opponent's turn, the Ashbringer would give
the hero attack power immediately, instead of on his turn.
Implemented Amani Berserker
Implemented Combo Mechanic

This is a very simple implementation that only count the number of cards
played each turn. I suppose we could actually store the exact cards
played and then count that array, but I currently doesn't know of any
situation where this should be of any use.
I.e., I don't know of any cards that have "If you have played card X
this turn, then this happens."
Fix for Combo Mechanic

Ooops.
Implemented Rogue Hero Power
Implemented Defias Ringleader

And a fix for the combo mechanic.
flake8 fixes
Added enrage mechanic.

Updated Amani Berserker to use this mechanic.
Implemented Silver Hand Knight
Added additional testing for Amani Berserker
Updated Character documentation
Merged changes from randomflyingtaco and fixed some formatting issues
Formatting fixes
Merge branch 'randomflyingtaco-master'
Implemented Stormwind Champion and reworked how auras work.

Previously, auras were called "board effects", but the new name is more
consistent with Hearthstone terminology.  Also, now instead of a pair
of functions, an aura is just an amount of increase to attack and health
Fixed a bug related to auras not affecting health correctly on silence