* Small timout for worker notification
It seems at the moment if a worker re-establishes notify stream (for example, if network flips or proxy breaks the connection) then we can see "no worker registered with this name" errors.
This change makes Notifier to wait for 30 seconds before failing, at the time of calling `Notifier#Notify` we know such worker exists.
PS not sure if we need to make the timeout configurable.
* Wait via context
* Make sure all `context`s for `Notify` is time bounded
* Lint issues
* Introduce WebSocket-based RPC v2
* go test: add -ldflags="-B gobuildid"
* No need to change the "controller.workerNotifier.Notify()" error message
* No need to modify Protocol Buffers/gRPC generated code
* rpcWatch(): explain that connection shouldn't be normally be closed
* Avoid "port forwarding failed: " repetition in error messages
* Improve comments and avoid repetition in IP resolution errors
* proxy.Connections(): require io.ReadWriteCloser instead of net.Conn
* Orchard Controller: implement an SSH server that acts as a jump host
* Issue a warning if the name used will be invalid in the future
* Further restrict uppercase characters in names in the future
The rationale is similar to https://github.com/kubernetes/kubernetes/issues/71140.
We won't want to munge the user's input and introduce subtle bugs doing
lowercase comparisons.
Nikolay Edigaryev
Fedor Korotkov