Apic drivers enhancements (second approach): L2 refactor
Apic drivers enhancements (second approach): L2 refactor

- refactor to leverage Client's transactional capabilities
- General refactor to improve the driver's reliability

Implements blueprint: apic-driver-enhancements

Change-Id: I4deb171381e62e70818218957d82b5e27954aeb9

Tehsmash/networking-cisco-nexus