Test in JavaScript and under the Grunt plus contributors guide

Hi guys,

Some updates for the project:

1. Added guide for contributors 'CONTRIBUTING.md'
2. Tests now in JavaScript  and moved under the Grunt 'grunt test'
3. Test now have folder structure in-tact with .'/lib' directory
4. Static test data moved under 'test/fixtures/' directory
5. Test file now must have '*.test.js' suffix
6. Cleaned up package.json from unuseful Grunt dependencies

Note that ```npm instal``` is required