Fix apt_proxy/ntp/vagrant plugins manifests
Fixed previous yaml load commit and added a tox.ini file.

DETAILS:
- Apparently a potential security issue with yaml.load vs yaml.safe_load.
  Like pickling, yaml.load could result in arbitrary code being run.
- tox.ini file includes the flake8 settings for this project, build spec for 2.7
  and line for eventually testing the project.
Merge pull request #73 from Rory-Finnegan/development

Fixed previous yaml load commit and added a tox.ini file.