* Install six before we upgrade setuptools.

See pypa/setuptools#964 for a few more details. Currently quite a few
travis and circleci jobs are failing because of that.

* Explicitly upgrade pip and setuptools in 'make update_deps' so for travis too.

* Potentially fix circleci

* Fix setuptools and potentially docs environments

* More explicitly install six and setuptools

* Add more requirements for docs

* Add pyparsing dependency