Upgrade piece changes RuleSet to KingRuleSet
Refactor Move

+ Deprecate move constructor; use (Piece, int) instead.
+ Add getPiece method
Refactor Board

+ Deprecate movePiece; added new method with (Move) arguments
= Change behavior of kingPiece
Update Board

= Changed Piece initialization methods to the new format.
= Changed getPieceAt to return null rather than a red colored piece
Add getLocation
Refactor Player.java

+ Added capability to create and send moves to driver without going
  through Rules (still needs to be finished though).
Fill out SingleRuleSet

SingleRuleSet now has complete logic for validating moves for Single-
type pieces and can determine if one can make a jump.
Add TODO to RuleSet

Some ideas/concerns/work added to RuleSet, concerning its behavior.
This is low priority, so this probably won't be addressed until later.