allow setting of mod_path
update gemfile (berks3, pin rspec)
- pin rspec due to https://github.com/rubygems/rubygems/issues/853
- fix metadata for test cookbook for berks3
Merge pull request #35 from heyinc/set-mod-path

allow setting of mod_path
allow setting of graphite options
red test
carbon configs only propagate when set to a value