Support for ifroute

bnc#897394, bnc#866250
I mean that whole term is constant except this `device` parameter. So in the end you can have something like
```
agent_descr = deep_clone(ROUTES_AGENT_TERM)
agent_descr.params.unshift(term(:File, "/etc/sysconfig/network/ifroute-#{device}"))
agent_descr
```