Allow to determine the version of libcouchbase

Change-Id: Ib0dca9701b3b2bc5d7556ec48262d9b1536ff502
Reviewed-on: http://review.couchbase.org/28491
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>