Shorten interface names to avoid too long names

This "fixes" #28
Merge pull request #34 from discordianfish/fix-too-long-if-names

Shorten interface names to avoid too long names
Give our ARP neighbors a nudge about the new interface

The new interface cannot be reached until the local switch learns about
its MAC address, which could take minutes. Sending a gratuitous ARP
moves things along so that the interface becomes reachable right away.