travis-unittest2: added unittest2, use mirrors
travis-unittest2: added unittest2, use mirrors

--use-mirrors is recommended http://about.travis-ci.org/docs/user/languages/python/#Pre-installed-packages

- added 2.6 and test in yaml

neizod/argcomplete,neizod/argcomplete,lisongmin/argcomplete,lisongmin/argcomplete,landonb/argcomplete,douglas-larocca/argcomplete,kislyuk/argcomplete,kislyuk/argcomplete,landonb/argcomplete,douglas-larocca/argcomplete