GTNPORTAL-2957: extracted shindig-related dependencies into a module to ...

...prevent issues with ehcache and jbossws-cxf with wsrp and wss :(

- Created org.gatein.shindig module
- Created org.json module used both by org.gatein.lib and org.gatein.shindig
- Cleaned-up org.gatein.lib module
- Added MANIFEST dependencies on org.gatein.shindig module in eXoGadgetServer war

Will require deeper testing to make sure things didn't break when dependencies got extracted.