instead of GET terminals/new
to be consistent with creating new notebooks.
We had to stop using GET notebooks/new
because browsers would create new notebooks when making preview thumbnails for commonly visited pages, etc.
I assume the same issue would apply to terminals
The websocket handler auth checking was calling clear_cookie(), which
threw an error because it doesn't make sense for Websockets. It doesn't
seem important, and we silence it in our other websocket handlers, so
silencing it here too.
