add py26 as a required testing env
make it a verbose run for tox py.test
make tests compaitble with python 2.6

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
Merge pull request #19 from alfredodeza/master

Make tests compatible with Python 2.6

Reviewed-by: Gary Lowell <gary.lowell@inktank.com>