OFStateManager: implement BSN VLAN counter stats request handler
OFStateManager: implement BSN port counter stats request handler
OFStateManager: add weak symbols for new stats interfaces

If Forwarding/PortManager don't implement these functions then the weak
versions will be used, and all counters will be returned as -1.
OFStateManager: optimize counter stats loop

This removes an allocate/free from every iteration. Involves reaching into the
wire buffer to avoid assertion failures.
Merge into master from pull request #74:
Update LOCI and fix group fallout (https://github.com/floodlight/indigo/pull/74)
add loxigen-artifacts submodule
remove generated LOCI files
remove generated locitest files
consume loci and locitest from loxigen-artifacts
delete extraneous loci files
delete extraneous locitest files
Merge into master from pull request #76:
Consume loci and locitest from loxigen-artifacts (https://github.com/floodlight/indigo/pull/76)
OFStateManager: send bad_request/eperm instead of hello_failed

A little better but not much.
OFStateManager: add minimal VLAN ID validation
indigo: add error handling comments to stats interfaces

The implementations should just leave all the counters with the default
"unsupported" value in case of error.
OFStateManager: factor out loci object truncation

This should eventually be moved to LOCI.
Merge into master from pull request #75:
BSN counter stats requests (https://github.com/floodlight/indigo/pull/75)
update loxigen-artifacts

Pulls in 32-bit build fixes, bsn_role_status, and bsn_controller_connections.
OFConnectionManager: implement bsn_role_status extension

This is a backport of the OpenFlow 1.4 functionality. When we support OpenFlow
1.4, the new ind_cxn_send_role_status function will send that message (to a 1.4
connection) instead.
OFConnectionManager: implement bsn_controller_connections extension

This extension allows the controller to query all configured controller
connections and their current state.