Bump version to v8.0.0-alpha.5
Bump version to v8.0.0-alpha.5

Change-Id: Ied1314fbb3110023e997fee546280269c082aa2f
Reviewed-on: http://review.couchbase.org/112577
Reviewed-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>
Tested-by: Charles Dixon <e13bf4498b4994e133fd3586350658dc4a59329a@gmail.com>

brett19/gocbcore