[sr-dev] HTTP/WS support for rtpengine

Hi gang, As of today, rtpengine adds support for HTTP and WebSocket interfaces (as well as HTTPS and WSS). Currently supported operations are accessing the CLI commands provided by the `rtpengine-ctl` CLI tool, and accessing the "NG" control protocol. These are both 1-to-1 mappings on top of the existing interfaces, just with a different transport protocol on top, which doesn't make for a pretty RESTful interface, but should otherwise be perfectly usable. It can also be further extended if necessary, with some additional operations already planned. There's a bit more detail at https://github.com/sipwise/rtpengine#httpwebsocket-support The "NG" protocol support in particular should be interesting to those who keep having problems with the UDP transport of the existing protocol, due to packet loss or MTU issues or otherwise. This makes it possible to switch the transport protocol to HTTP or WS while retaining full compatibility with the existing control protocol. This isn't currently implemented in the Kamailio module for rtpengine, but if someone feels like giving it a shot, then by all means feel free. It may also be of interest to those who want to control rtpengine from JS etc for example. Cheers Richard