First updates for getting game mechanics down
Completed implementation for adding a new piece and advancing current
piece within the canvas
Updated the following:
    - Modified BigSquare so that length of an individual square's
      side is passed as a parameter to the constructor
    - Added function to return left, right & bottom-most squares
      of BigSquare
    - Added correct border+fill of individual squares
    - Added movePieceLeft, movePieceRight, and movePieceDown functions
    - Fixed pausing/continuing of game
Cleaned up the advancing of the current piece implementation
Added keyboard bindings (down, left, right) to currently active piece
- Moved the attaching to events to a separate function
- Added comments to the TetrisGameController module
- Added the checking for line completion
- Added the udpate of the metrics values when a line is completed
Merge pull request #2 from Daynesh/game-mechanics

Game mechanics