Ignore test files from automake

Change-Id: I610f214ef9a6c5f85d15ab96324ab14102b39875
Reviewed-on: http://review.couchbase.org/29071
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Tested-by: Chiyoung Seo <chiyoung.seo@gmail.com>