In case of connection failure, the user can either maintain the connection
or modify it.
Split up `add_connection_to_ui' into `make_conn' and `register_conn'
to handle separately the object creation and its registration in the
list of connections (ui and conf).
Solves: https://bugzilla.redhat.com/show_bug.cgi?id=617386
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>