CentOS/RHEL-friendly additions

Hi,
Thanks for the puppet-graphite module.  I was looking for a "light" puppet module that gets carbon and graphite installed via pip and running on gunicorn without having to worry about setting up apache or nginx configs.  I may set that up later, but this is a nice module to get graphite up and running without any extra hassle.

I made some changes to make this puppet module compatible with Red Hat/CentOS.  I added a few class params as well, but left the defaults set to what you had before so it shouldn't be too intrusive.  I was getting a warning about SECRET_KEY not being set in settings.py/local_settings.py, so I had to move local_settings.py to a template and add a param for that.

Cheers,
Jason