wicd: fix wicd-curses with new urwid
See e.g. https://bugzilla.redhat.com/show_bug.cgi?id=894646 — without
this patch, wicd-curses throws an AttributeError on startup. The patch
is a cut-down version of the one added there by Pavel Zhukov.
authored by Matti Niemenmaa and committed by Cray Elliott 85e405c1 29b3353a