* Make new path for signalling v1.5 support.
To be able to support newer clients to interact with older servers, move
signalling v1.5 to new path (`/rtc1`). On the new path, `join_request`
is required and single peer connection is used.
With the existing path `/rtc`, single peer connection is still supported
if `join_request` is used.
Newer clients connecting to old server should follow
1. Try new path WebSocket
2. If that fails, try new path validate at `/rtc1/validate`.
3. If the above gets a 404 which will happen with older server, revert
back to old path and signalling 1.0.
Open to suggestions on path name.
* test on both paths
* change path from /rtc1 -> /rtc/v1
* test all rtc service path combinations
cd99fec2e7