graphite: Fixes to work with trusty

- Do not use setup_environ. Is deprecated. Set an env variable
  instead, which is supported on more versions of Django
- Location of graphite's manage.py has changed. While this is
  ostenibly stupid, workaround it for now by branching on
  distro name

Change-Id: I736934fde4a47d3d449cd76b56313aa603b85eff
Merge "graphite: Fixes to work with trusty" into production