multipath: libudev cleanup and bugfixes

multipath: libudev cleanup and bugfixes

get_refwwid wasn't working anymore, since it wasn't setting the path's udevice.
Also, cli_add_path was dereferencing a NULL pointer (pp). Finally, there were
a number of places where udev devices weren't getting dereferenced when they
should have been, causing memory leaks.  This patch cleans these up.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>