invokation of tox fails due to missing execfile

[krichter722]

After

git clone https://github.com/kdeldycke/kdenlive-tools.git
cd kdenlive-tools

invokation of tox fails because of missing execfile. According to python --version I'm running 2.7.8, but there might be an issue due to the fact execfile is no longer present in python3 (see http://stackoverflow.com/questions/436198/what-is-an-alternative-to-execfile-in-python-3-0 for explanations and solutions). I don't know so well what tox does in detail, so it might be a minor issue, but it should be explained, tox should fail with a clearer error message or the invokation changed to no-op if requirements aren't fulfilled.

I'm running python 2.7.8 on Ubuntu 14.10.