(SERVER-18) Added puppet config opts
(SERVER-18) Can use headers for cert CN and auth
(SERVER-18) global config to dissallow cn header

The puppet.conf settings, ssl-client-header and ssl-client-verify-header
are potentially dangerous so an explicit Puppet Server config option was
added. This option is :allow-header-cert-info and it's found in the
global config section.
(SERVER-18) Added tests
(SERVER-18) Moved config key to master section
(SERVER-18) Malformed DN's no longer throw
(SERVER-18) Docs update
(SERVER-18) Removed unneccessary require
(SERVER-18) Manually checking DN validity
(SERVER018) Fixed typo
(SERVER-18) Added documentation
(SERVER-18) Corrected formatting
(SERVER-18) Updated docs
Merge pull request #211 from dankreek/SERVER-18/add-x-client-dn-support

(SERVER-18) Add x-client-dn and x-client-verify support