Feature : Add support for gzipped ingestion

1. Sender/Customer can start ingesting gzipped data, by just setting the `Content-Type` header to `application/gzip` http://tools.ietf.org/id/draft-levine-application-gzip-03.html#rfc.section.2.1.
2. If gzip compression is used and `Content-type` is not set properly, it will return a `BAD_RESULT`.