Jobs and Roles frequently have the same variable names, so use
create unique directives and roles for each so that they are
easy to disambiguate.
This lets us say :jobvar:`tox.environment` rather than
:var:`job-tox.environment` which seems a bit arbitrary.
Change-Id: I9d72d11bfdb700037a6a08f92a2dbfa95ee519ad
ad1188ba7f