ifName should be derived from baseport number if not available

[Morten Brekkevold]

when a device doesn't respond to IF-MIB::ifName, ipdevpoll substitutes the value found in IF-MIB::ifDescr. Oftentimes, the ifDescr value is quite verbose. This breaks the port layout in ipdevinfo, which is designed for port numbers or short names (such as `Gi1/2`).

If an interface is found to be a switch port, but no ifName value can be collected, ipdevpoll should substitute the dot1dBasePort number for the ifName. If not a switch port, it should fall back to substituting ifDescr as is being done today.

[Morten Brekkevold (mbrekkevold)]

fix here: http://metanav.uninett.no/hg/default/rev/394c9253ae6d

This fix depends on the bridge plugin running before the interfaces plugin of the ipdevpoll inventory job - the config file is updated by this patch as well.