[TIMOB-27129] Migrate unit testing suite to Karma and stock mocha/should.js

Our [titanium-mobile-mocha-suite](https://github.com/appcelerator/titanium-mobile-mocha-suite) is currently using a lot of custom tooling to get unit testing to work. This includes custom versions of mocha, reporters and assertion libraries. With our latest efforts to make our runtime more node compatible and the new [karma-titanium-launcher](https://github.com/appcelerator/karma-titanium-launcher) we can move away from custom built testing tools and use the stock version as is. This requires a migration of our unit testing suite to use Karma and would need the following changes: - Add Karma and the required plugins for mocha and should.js - Apply required changes to the test files so they are compatible with Karma - Modify the existing [test.js](https://github.com/appcelerator/titanium-mobile-mocha-suite/blob/master/scripts/test.js) to let Karma handle the whole unit testing process. - Adopt the existing customizations made to mocha and should.js and apply them to the Karma environment