* 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
```
timeit result for 10000 iterations of expanding '/d' (lowered the count in the code afterwards)
# 2.7.5 3.3.2
# FilesCompleter 75.1109 69.2116
# FastFilesCompleter 0.7383 1.0760
```
- does not display prefix dir (like bash, not like compgen), py.test /usr/<TAB> does not show /usr/bin/ but bin/