strip whitespace from card values
ordered COLORLESS_X before the various COLORLESS_<N> constants, as costs that contain both an X and explicit colorless mana always have the X first
 * added support for controlling acceptance of the tap cost
 * added collapsing of multiple explicit colorless costs
 * ignore all non-recognized cost symbols
accept full symbols (brace-wrapped) when parsing costs, rather than assuming every individual character is a symbol
added isSymbol next to fromSymbol
handled CostType's IllegalArgumentExceptions on fromSymbol w/in the parse method
added .travis.yml for groovy builds on Oracle JDK 1.6