If the COUCHDB_ADDR environment variable is set, it should point to a
running instance of CouchdB to by used by tests. When the environment
variable is not set, an containerized instance of CouchDB will be
launched on an ephemeral port of the loopback adapter.

Change-Id: If9c7f7e2dc5fcc493f8409aee96667382be95353
Signed-off-by: Matthew Sykes <sykesmat@us.ibm.com>
Signed-off-by: Will Lahti <wtlahti@us.ibm.com>