Add CentOS caveats
puppetdb_ssl renamed to puppetdb_ssl_verify
Merge pull request #51 from yo61/feature/rename_puppetdb_ssl_to_puppetdb_ssl_verify

puppetdb_ssl renamed to puppetdb_ssl_verify
Merge pull request #50 from Paulche/master

Add CentOS caveats
Allow puppetboard user's supplementary groups to be set
Add note about adding puppetboard user to puppet group
Update README with additional information regoarding SSL certificates
Fix formatting in README