Store packs as a hash keyed on pack name.
Store packs as a hash keyed on pack name.

Issue #129.

Store packs within the Deck object as a hash instead of an array, so
that we can interrogate them by pack name instead of having to iterate
through it each time.

jshholland/pah-irc,grifferz/pah-irc,jfautley/pah-irc