MB-19339: Make getConnection virtual
MB-19339: Make getConnection virtual

This allows each test batch to override it if it needs
special setup to the connection (like always authenticate
as a given user)

Change-Id: Ia452160d7f265307d7145a9081dcb06e1aac67ea
Reviewed-on: http://review.couchbase.org/73431
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

daverigby/kv_engine,daverigby/memcached,daverigby/memcached,couchbase/memcached,couchbase/memcached,couchbase/memcached,daverigby/memcached,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,couchbase/memcached,daverigby/memcached