Made TapTest only run against Membase.
Made TapTest only run against Membase.

I'm aware that tap works for memcached, but since most people
are still on a tapless version I don't want to run the tests
against memcached yet.

Change-Id: Ia5d1d943a59d91ec59419643e9c0af10ae5166ba
Reviewed-on: http://review.couchbase.org/7936
Reviewed-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>
Tested-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>

tootedom/spymemcached,douxiaozhao/java-memcached-client,tootedom/spymemcached,1and1/java-memcached-client,tootedom/spymemcached-1,HubSpot/java-memcached-client,HubSpot/java-memcached-client,dustin/java-memcached-client,Agilefant/spymemcached,Agilefant/spymemcached,tootedom/spymemcached-1,douxiaozhao/java-memcached-client,resrugam/java-memcached-client,tootedom/spymemcached,resrugam/java-memcached-client,HubSpot/java-memcached-client,Agilefant/spymemcached,dustin/java-memcached-client,resrugam/java-memcached-client,couchbase/spymemcached,dustin/java-memcached-client,tootedom/spymemcached-1,douxiaozhao/java-memcached-client,couchbase/spymemcached,couchbase/spymemcached