Fix CORS for additional_lookup urls.

Currently OPTIONS are not handled within the app
so there are no CORS related headers in the response.
Merge branch 'develop' of https://github.com/petrjasek/eve into petrjasek-develop
Tests for CORS support on item endpoints.
CORS for additional_lookup urls
Petr Jašek
Merge branch 'petrjasek-develop' into develop