WIP: Vagrant

[odscjames]

Add virtualenvs
Change sed to match current values

Still can't build docs tho?

sphinx-build -q -b dirhtml standard/docs/en build/en

Exception occurred:
  File "/home/vagrant/standard/.ve/lib/python3.5/genericpath.py", line 143, in _check_arg_types
    (funcname, s.__class__.__name__)) from None
TypeError: join() argument must be str or bytes, not 'PosixPath'

[jpmckinney]

I think the docs might require Python >= 3.6 (we haven't had a reason to support older versions).

[odscjames]

I've updated Vagrant to work on Bionic for Python 3.6 - need to test this.