Merge pull request #91 from changbl/working

Update arp eval scripts
Failover version: normal functionality

Fix bugs introduced over normal operation of controller
Merge pull request #93 from powerist/failover

Failover version: normal functionality
Fix bug of detecting live migration
Merge pull request #94 from powerist/fixmigration

Fix bug of detecting live migration
Add logger info for handle migration and comment out an impossible case