Improved the WebWorker RequireJS shim, so it's closer to the AMDJS spec

Improvements:

 - It's now possible to list dependencies that gets loaded before calling the factory-function
 - Relative paths without folders (./foo) now works properly
 - The define()-behaviour is now tested by four unit-tests
Merge pull request #1616 from fangel/patch-1

The require() and define() methods for workers does not conform to the AMDJS spec