Tidelift has launched a new marketing campaign as outlined here:
* https://forum.tidelift.com/t/task-enhancement-marketing-the-tidelift-subscription-to-your-users/321
This PR splits the previous "sponsor" information into two, Open Collective
and Tidelift (as they have very different target audiences).
Also took the opportunity to reorder some items at the end of
the contents page in a manner that I believe make more sense.
* Update setup.py requires and classifiers
* Drop Python 2.7 and 3.4 from CI
* Update docs dropping 2.7 and 3.4 support
* Fix mock imports and remove tests related to pypi's mock module
* Add py27 and 34 support docs to the sidebar
* Remove usage of six from tmpdir
* Remove six.PY* code blocks
* Remove sys.version_info related code
* Cleanup compat
* Remove obsolete safe_str
* Remove obsolete __unicode__ methods
* Remove compat.PY35 and compat.PY36: not really needed anymore
* Remove unused UNICODE_TYPES
* Remove Jython specific code
* Remove some Python 2 references from docs
Related to #5275
* Changed "index" to be more similar to the README (#1708).
* Fixes numerous issues like missing documents, syntax errors, etc (#1829, #432).
* Mention all docs in "contents.rst" so it's easier for users to locate (#1112).
* Add doc generation and checking to Travis and AppVeyor, to avoid re-introducing errors.
Fixes#432, Fixes#1112, Fixes#1708, Fixes#1829
