Some initial POST work for JWS Api

This patch consists of arrangements that give the ability to the webservices API to create new resources, plus some minor corrections regarding CORS (Cross browsing) using jQuery.

To test this patch, you can found a full integrated Joomla! package here:

https://github.com/fastslack/joomla-cms

This patch was created following the Joomla CMS Web Services API Specification: https://docs.google.com/document/d/1FVKGlV6BN6pu-YH2WR2pQHE3Ez7M6r7LD417GSw9ZSo/edit#heading=h.w1gkp7elxxwo