Fix: use NULL url for load live session

For a live session, the control and data URI are mandatory thus pass
NULL to the create session so we can set them afterwards by a set
consumer URL call.

net:// can't be used for control and data so this fixes the uri to url
string by printing "tcp://" instead of net:// which is more accurate and
the good way to actually print the URL to the user.

Fixes #767

Signed-off-by: David Goulet <dgoulet@efficios.com>