Drive-by lint!

- the module parametrizes the user/group name, but the upstart config
  hard-coded 'wikimetrics' for both.
- user resources autorequire their group, if Puppet is managing both resources.
- file resources autorequire managed parent paths
- SysV-style init.d compatibility for Upstart jobs has been obsolete for years.
- The if !defined trick is not a true workaround for duplication definitions,
  since they only work if the other definition is conditional too, because the
  order in which resources are evaluated is undefined.

Change-Id: I1c343eb41c11f2e1a04cc3c6b3769be5157c5dc7