Install pillow before running sphinx

[wiredfool]

Fixing sphinx on travis.

[radarhere]

Just curious, what problem does this solve exactly?

[wiredfool]

It fixes this error, (from https://travis-ci.org/python-pillow/Pillow/jobs/100226767 : (a passing test))

Exception occurred:
  File "conf.py", line 59, in <module>
    import PIL
ImportError: No module named PIL
The full traceback has been saved in /tmp/sphinx-err-XWZI0I.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
make: *** [html] Error 1
sphinx-build -b linkcheck -d _build/doctrees   . _build/linkcheck
Running Sphinx v1.3.3
making output directory...
Exception occurred:
  File "conf.py", line 59, in <module>
    import PIL
ImportError: No module named PIL
The full traceback has been saved in /tmp/sphinx-err-jsNZyt.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
make: *** [linkcheck] Error 1
~/build/python-pillow/Pillow

[radarhere]

Ah ok, thanks for that.