Sphinx-argparse

* Support for aliasing arguments 22 (Campbell Barton)
* Support for nested arguments 23 (Campbell Barton)
* Support for subcommand descriptions 24 (Campbell Barton)
* Improved parsing of content of `epilog` and `description` 25 (Louis - https://github.com/paternal)
* Added 'passparser' option (David Hoese)

* Bugfix: Choices are not always strings (Robert Langlois)
* Polished small mistakes in usage documentation (Dean Malmgren)
* Started to improve man-pages support (Zygmunt Krynicki)

* Improved error reporting (James Anderson)

* Fixed stupid bug, prevented things working on py3 (Alex Rudakov)
* added tox configuration for tests

* Remove the ugly new line in the end of usage string (Vadim Markovtsev)
* Issue 9 Display argument choises (Proposed by Felix-neko, done by Alex Rudakov)
* :ref: syntax for specifying path to parser instance. Issue 7 (Proposed by David Cottrell, Implemented by Alex Rudakov)
* Updated docs to read the docs theme

Fix problem with python version comparison, when python reports it as "2.7.5+" (Alex Rudakov)