Names for priority levels are wrong

[alvestrand]

rtcweb-transport: "normal", "below normal", "high" or "very high".
tsvwg-rtcweb-qos: “very low”, “low”, “medium”, “high”.
WEBRTC-PC: enum RTCPriorityType {
"very-low",
"low",
"medium",
"high"
};
The majority should win.