JCBC-560: Also expose versioning information.

This changeset is inline with the latest core-io changes to
expose the actual version in the user agent string, as well as
in the environment to immediately show which version gets used.

Change-Id: I47e7921c8c4ee88309adbfdeaf68f06db48909ef
Reviewed-on: http://review.couchbase.org/41429
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>