vispy-viewer: make it run in jupyter notebooks using jupyter_rfb

[sanjayankur31]

The vispy bits should work in jupyter notebooks/jupyterlab using jupyter_rfb. We need to test this out and make any changes necessary to get it to work

See also: vispy/jupyter_rfb#89

[sanjayankur31]

Works, will open new issue for multiple visualisations not working.