I read Sentry client development guide and Sentry interfaces document, but I didn't find anything about putting "project" in json request, so I removed this field. So if you find where it is, you can tell me.
http://sentry.readthedocs.org/en/latest/developer/client/index.html#building-the-json-packet
http://sentry.readthedocs.org/en/latest/developer/interfaces/index.html#interfaces