* Improves testing
* Adds karma-sourcemap-loader
* Adds karma-preprocessor-rollup
* Moves testing Rollup building to Karma
* Enables sourcemaps in tests
* Fixes#2051
* Updating tests to reflect discrepancies with Phantom@^2
* Trying karma-coverage-istanbul-reporter
* Still not working...
* chore: make coverage report of src files
* test: add c3.css
* fix: fix test case of mouse events
* chore: update codecov module
* Adds codecov.yml to ignore polyfill.js
* chore: exclude src/polyfill.js at istanbul layer
* chore: remove rollup-plugin-istanbul dep because not used
Code to access objects by path was taken from the solution of
http://stackoverflow.com/questions/6491463
When JSON objects are used to load chart data, nested / inner objects and
arrays can now be loaded, too.
See additional tests in spec/data-spec.js for examples, how to access nested
JSON object values