The comment above that function says: "This function can be a lot more
exhaustive, ...", so let's be.

Check for collisions between routes in the system and static routes
being added explicitly from the <route/> element of the network XML.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1094205Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>