.gitignore with Idea project files and new header 

First commit is rather self explainable. 

Second fixed issue I got when trying to read a Location header after posting a document (to figure out _id of newly created document). But my browser kept refusing saing "Refused to get unsafe header".  So I followed a hint from:
http://stackoverflow.com/questions/7700151/refused-to-get-unsafe-header-location
and added "Access-Control-Expose-Headers" header.