Added requirement of a `_useTimer` boolean in the IModelRules interface, updated unit tests
Added _useTimer and get/set methods to GameRules class, added unit tests
Added _timerContainer and get/set functions to AppView class; added unit tests
Added AppView.__createTimerContainer() method and unit tests
Added AppView.updateTimer() method and unit tests
Updated AppView.__construct() to create, set, and add timer container to the DOM
Removed __startGameTimer() method from GameController class
Added _useTimer boolean to TestRules mock object in GameController unit test file
Added unit tests for GameController.beginGamePlay() method
Added __startGameTimer() method and __timer property to CardGameApp, added unit tests
closes #10, closes #11, closes #12, closes #13
Added some basic styling, and created a mock Game that will load in browser when running devbuild/dev.html while dev_server.js is running