Add JS Code style tests

* fix #149
* fix #166
Merge pull request #167 from mozilla/add-jscs

Add JS Code style tests
Add browser-based, mocha API tests (#148)
Add new test info to README
Fix IE 10 null/undefined bug (fix #161)
Wrap localStorage.key in try/catch (fix #162)
Update Changelog
Add version info to CHANGELOG
Add info about running tests locally-only
Remove test-server task