Upgrade SPY to 2.9.0 (served from maven central).

Change-Id: I281e60a8dff9b6a5d8d7504a7f07fe1904efd8eb
Reviewed-on: http://review.couchbase.org/26778
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Reviewed-by: Deepti Dawar <deepti.dawar@globallogic.com>