remove lldpa
Implement LLDPA module

Summary:
For TX_REQ, it sends out LLDP PDU for a specified interval
For RX_REQ, it expects to receive incoming LLPD PDU for a
specified interval. It sends Timeout Msg to controller if
it doesn't receive LLDPDU within that interval.
Switch forwards LLDPDU as packet-in to the controller if
LLDPDU is unexpected (port not set or data not matched)
Some cleanup and move some defs to an internal header
Address review comments
Return failure if slot_num != 0
Handle only LLDP packet for now
Address review comments
Use indigo_strerror
Merge into master from pull request #4:
Lldp 2 (https://github.com/floodlight/switchlight-common/pull/4)