Making dogtail code perform both with Python2.7 and Python3.
Biggest thanks comes to *Martin Simon (msimon@redhat.com)* for going through
the entire framework and writing many new unittests for yet uncovered modules

Please, see the content of python3 branch for the individual commits done
by respective authors on the paralel version of dogtail.

*From now on, we have a single codebase for both major version of Python.*