Don't bother doing the prepareDisconnect dance if the connection is
already broken. This avoids having to wait until the connection times
out when a slave gives up on a current connection and starts a new one.
Provide a convenience method for checking if the Master-Slave link is
fully online via a .connected property. This is true if the link has
been establised, is not in the dropped state, and not in the process of
disconnecting.
Add /api/upload-save endpoint that streams the data via the slave
assigned to the target instance to the instance saves directory, along
with a ctl command and web interface button to do the upload.
Hornwitser