Add istanbul to Build System

[CharlieGreenman]

Currently Mocha and Chai are implemented with ES6. However, the build is currently lacking istanbul, which gives the following error: No coverage information was collected, exit without writing coverage information.

It might be related to the following: gotwarlost/istanbul#262

[CharlieGreenman]

Look into using nyc. Seems to make more sense with what we are trying to achieve.

https://github.com/istanbuljs/nyc

http://stackoverflow.com/questions/33621079/running-mocha-istanbul-babel

[CharlieGreenman]

Also make sure to include cross-env, so that babel-istanbul is picked up when using a test environment: https://github.com/istanbuljs/nyc

[CharlieGreenman]

Issue solved. Using the following command
"test": "istanbul cover _mocha",
and the following options in mocha.opts

--colors
--reporter spec
--timeout 1000
--check-leaks
--compilers js:babel-core/register
--require babel-polyfill
--recursive
--sort
src/app/**/*.spec.js

Credit must be given where credit is deserved. Config for mocha.opts found in the following thread thread. However, used mocha.opts instead of conf, and did not use all of npm task as it is superfluous.