Use --quiet option for pip on travis runs

The amount of output is insane, and makes scanning the logs really annoying.
Fix Sphinx HTML builds on travis

Ugly bug, should have caught it when switching build order around.
Use -n for sphinx-build to report reference errors
Fix --name link in getting started doc
Use qualified name for exceptions in docs

This allows intersphinx to create links to the upstream docs.
Move the XDG_DATA_DIRS info to appendix

It doesn't really need to be there, and it is the start of simplifying the docs
for the common case.
Fix error reporting for travis's SPHINX_BUILD rule
Remove cheeseshop extension from requirements file
Use a pre-generated blockdiag image in docs

Unfortunately the blockdiag dependency chain doesn't support the full range of
environments we need.
[Tr] Fix headings for versioning hints
Merge branch 'feat/sphinx_updates'

* feat/sphinx_updates:
  [Tr] Fix headings for versioning hints
  Use a pre-generated blockdiag image in docs
  Remove cheeseshop extension from requirements file
  Fix error reporting for travis's SPHINX_BUILD rule
  Move the XDG_DATA_DIRS info to appendix
  Use qualified name for exceptions in docs
  Fix --name link in getting started doc
  Use -n for sphinx-build to report reference errors