The Python3 dev doc is more general than just modules
* Rename it to make that obvious.
* Move generally applicable Python3 information to the Controller section
* Add a Py3/Py2 section on formatting strings
* Fix code-blocks to highlight as python
* Enhance python3 support page
* Add Python3/Python2 compat note
* Update module_utils.six to latest
We've been held back on the version of six we could use on the module
side to 1.4.x because of python-2.4 compatibility. Now that our minimum
is Python-2.6, we can update to the latest version of six in
module_utils and get rid of the second copy in lib/ansible/compat.
