Use python 3.5 in .travis.yml
Use python 3.5 in .travis.yml

This is a workaround for TravisCI's broken support for Python 3.5. I.e.
python 3.5 is not available in the test environment unless we "trick"
TravisCI into ensuring it is installed.

SanDisk-Open-Source/pyvcd,jpgrayson/pyvcd