(Travis) Merge remote-tracking branch 'origin/develop'

Set travis image to look a master

* origin/develop:
  Use skimhub's repo for travis
  travis test py 2.6 and 2.7
  travis image
  travis setup
More py3.3 compat changes. Remove unused type classes, import unicode literals
travis py 3.3
Tests pass in python 3.3

Import py3.3 stuff from __future__
Various checks to change behaviour in py3
update lxml version
Use six todo py3.3 compat stuff
Output __str__ in the given encoding

Removes need to is PY3 checks
Merge pull request #6 from minimal/py33

Py33 compatibility