Attempts to fix #97
Attempts to fix #97

At least for now, this should help to get the build to pass on Travis.
We need to get this netlify_deploy dependency onto PyPI to avoid
potential breaking changes when users install Statik.

This also updates the PyYAML dependency for a potential security issue
in the dependency.

thanethomson/statik,thanethomson/statik,thanethomson/statik