a bit of refactoring
Refactorings

* Refactored parcheesi.js
* Created new test_utils.js file to store tests that get repeated
* Completed first test on gameplay.js
Minor refactorings

* Fixed some duplicated references on CONSTANTS.colors
* Added dependency colors (this will help draw the board later on)
More refactorings for tests

* Added sinonJS library. Needed for mocking
* Added some examples of mocking on gamplay.js tests
* Made three additional tests pass
* Simplified the use of the colors CONSTANT
* Added test_utils (missing from latest commit)