New css loader plugin

Following of PR #213. Modification since last update of PR #213 is in this commit : https://github.com/clmath/delite/commit/1ff5c621f85ba125df715d1cd85f60f8e9a06341.

Thanks for adding the test.   Is there any reason to have a function called `setGlobalConfig()` which is then immediately called?   Why not just call `require.config({...})`?