Define Worker.postMessage for the non polyfill version

Tests are passing on FF and Chrome
Update grunt-contrib-connect

Servers wouldn't start when specifying `*` as hostname
The web worker tests can only run if supported by the browser
Ports are not optional with window.postMessage on Internet Explorer
IE and JSHint compatibility
Remove absolute urls in fixtures
Merge pull request #9 from Cyril-sf/browser_compatibility

Browser compatibility