Fix warnings from ruby like this:

/var/lib/puppet/lib/puppet/provider/sensu_client_config/json.rb:82: warning: parenthesize argument(s) for future version
/var/lib/puppet/lib/puppet/provider/sensu_check/json.rb:64: warning: parenthesize argument(s) for future version
Merge pull request #178 from notanisp/fix_ruby_warnings

Fix warnings from ruby like this: