Add the ability to specify a graphite graphTemplate to use

Graphite Function: https://graphite.readthedocs.org/en/latest/render_api.html#template

This allows you to easily use color schemes available on your graphite server. Which can be defined in graphTemplates.conf.

For example:
https://gist.github.com/mleinart/1235397


The only issue is graphiti will override the colors it specifies. These can be set to appropriate defaults and the theme will still be used for the actual lines.