Faucet

* Ryu 4.23
* Synchronize Prometheus DP port status when DP connects
* Fix extraneous broadcasts to controller when stacking (and don't learn broadcast sources from core to edge, reducing edge switch flow table sizes)
* FAUCET can send/receive LLDP packets with OUI TLV describing DP ID (for cabling/link verification)
* Log L3 dest address (if any) when learning
* Learning scale improvements (test up to 4096 hosts/switch)
* ACL output can do multiple ports
* Test meters with OVS

* Fix learned host reporting/counting (bug introduced in 1.6.24)
* Fix dead L3 neighbors not being expired
* Workaround for stale netns in hairpin int. test
* Re-add bgp_connect_mode config option (e.g. peer can be set passive)
* Explicitly decode of_dp_desc_stats labels as UTF8.

* DO NOT USE 1.6.24 (see 1.6.25 release notes)
* Upgrade to OVS 2.9.0 and DPDK 18.02
* Increase L2 and L3 scale baseline to 1024 and 2048 hosts respectively (many reductions to packet in processing, state expiry, and Prometheus export costs)
* Gauge logs port max/speed changes
* Rabbit MQ support for Pi
* Fix incorrect use of thread for Prometheus client (caused occasional data truncation)
* Gauge no longer needs empty prometheus_addr.
* Fix stacking config changes not being processed via cold start.

* Remove CouchDB support
* Minor optimizations in L3 resolution path
* Don't configure flow removed notifications if not required
* LACP packets could be truncated
* Don't use OFPP_LOCAL port for test

* Increase test coverage to 75% and enable code coverage reporting (https://codecov.io/gh/faucetsdn/faucet)
* Move FAUCET pipeline config to own file (faucet_pipeline.py)

* Tests: Add coveralls test coverage reports to project
* Tests: Improve unit test coverage to 73%
* Enhancement: Refactor Ryu code into a new RyuApp class
* Enhancement: Add --display-labels option to fctl