bindings: remove pending request when getting a result

Requests to the IOProcess are not removed from the
pendingRequests dictionary when returning,
and will cause a memory leak.
Popping the returning result will take care of this
leak (partly).

Change-Id: I961c70877271339a2899c375cd134aa2f692c866
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1130045
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>