removed vulnerable libs versions

fixed prob with builtin slots

Merge pull request #1 from medecau/master

improves speed on slot instantiation

improves slot parsing speed

fixes code style issues listed by pycodestyle tool ran over the test files

fix tox config lint dependencies

removes python 3 from the tox config as this is going to be a lot of work and one needs to see some green to feel motivated

fixes code style issues listed by pycodestyle tool

fixes errors identified by pylint

fix tests for python2.7

fixes import errors

update tox config to include python 2.7

update tox environment list

adds tox and travis-ci config files