This implements templating using the jinja2 module.

Other minor changes include:

- Now template variables can't contain '-', so replace this
  character by '_' in the template and profile examples.
- Add image_type to the template and profile examples.
- Add the --debug-vars option to the submit job command
  to show undefined variables in the template (use with caution).
- Include the jinja2 dependency in the setup.py installer.