Last Python2 release

• new: 'docs.sphinx' and 'docs.upload' task (to PyPI/WebDAV/Artifactory)
• new: convenient control of 'sphinx-autobuild' daemon
• new: added 'test' namespace and 'tox' task
• new: 'release.pex' to create PEX artifacts
• new: optional inclusion of PyRun in PEX artifacts
• new: 'release.bump' to create unique development versions
• new: build a DEB package (new 'deb' task)
• new: 'devpi' namespace with a 'refresh' task
• new: added 'freeze' as a root task
• new: 'jenkins.description' to display project metadata in the Jenkins UI
• new: support for projects with 'py_modules'
• new: 'util.filesys' module with a 'pushd' helper
• new: 'fail' helper function in 'rituals.easy'
• new: 'with_root' param for FileSet.walk()
• chg: 'test.pytest' as the default in 'test' namespace
• chg: 'prep' renamed to 'release.prep'
• chg: added '--clean' option to 'test.tox', and 'clean --tox'
• chg: exclude SCM dirs from 'clean'
• chg: improved autoenv script
• chg: better HTTP error reporting for docs upload
• chg: more unit tests (still missing a lot)
• chg: Python 3.4 support
• chg: Python3 is now the workdir default
• fix: non-git workdirs are handled correctly in 'release.prep'
• fix: support for Invoke v1 (ctask rename)