Shifting API functions to RESTful HTTP methods

Added method overrides in POST function and beginning of study-creation logic. Moved study-update logic to the PUT function and added a stub for DELETE.
Adding simple CORS support (no tweaks to web2py)

This should respond to CORS "preflight" requests, allowing any domain to use the OTOL API. If we have problems with this, we might need to patch web2py/gluon/globals.py to allow the 'OPTIONS' request_method.
Merge pull request #30 from OpenTreeOfLife/restful-api-methods

Shifting API functions to RESTful HTTP methods