Removed frame can knock down pins function
Corrected README
Game can add frame
Game total score should be zero at inception
Game can calculate total score
 A roll can knock down a pin
A roll can be added to a frame
A strike knocks down 10 pins in a roll
Changed frame knows its score spec
A frame can have a spare
A frame can have a strike
Changed syntax for isStrike and isSpare
Game can calculate a trike bonus