Switch from Paste to python3 compatible wsgi components
First pass at Python 3 compatibility.
All but one test passes. That error is only a test artefact due to gawel/WSGIProxy2#7.
Needed to remove wal-e as that is blocked by gevent. It can be moved to a separate buildout or virtualenv.
Fix WSGIProxy2 so that all our tests pass on Python3
Use subprocess32 on Python2
Ensure wsgi environ is native string type
Python 2/3 compatible PATH_INFO parsing
Move wal-e to a separate virtualenv
Try to run non-browser tests with python3.4
Avoid redundant build
Try new travis containers
Tell node-gyp to use python2.7 even on python3 build
Use a logger that seems to work
Try to avoid InvalidInstanceID.NotFound errors
Actually create wal-e virtualenv
Try caching eggs and npm cache
Reduced versions.cfg now wal-e is installed separately
Use tarballs for WSGIProxy2 and jsonschema
Merge remote-tracking branch 'origin/master' into python3-compat

Conflicts:
	versions.cfg
Merge pull request #572 from ENCODE-DCC/python3-compat

Python3 compat