Validator ssl

The ```defined``` function used to set ```$puppetdb_port``` as originally used doesn't work here, the default of 8081 is set no matter what. Switching to ```defined(Class['puppetdb'])``` seem to fix that.

Also, because the ```use_ssl``` parameter in the ```puppetdb_conn_validator``` resource is false only if the ```puppetdb_port``` is 8080, you can't set a different port using ```::puppet::config::puppetdb_port``` without also setting ```use_ssl``` to true which might not be what you want.

I've added an extra parameter ```puppetdb_disable_ssl``` to the class so that when the Puppet Master and the PuppetDB are on separate servers you can still set a non-standard ```puppetdb_port``` whilst using plain HTTP.

I'm still not sure the logic we're using here is that good though but it is hopefully an improvement.