Include configuration.h from generated_configuration.cc

Change-Id: I3f6181e9e2b9c82b2528e9f05f8d5c1a59c1f0be
Reviewed-on: http://review.couchbase.org/29969
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>