TensorBoard for Open OnDemand

Hi Kilian
This is looking good, thanks. However I tried to use the twisted pip/conda packages as an alternative to installing rpms, but i had errors with

 >>> from twisted.web.error import ForbiddenResource
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'ForbiddenResource'

I noticed that ErrorPage, NoResource and ForbiddenResource in twisted.web.error were deprecated since 9.0 and are removed since twisted web v12 (in 2012), so will be problematic for recent versions.