apache_c2c::vhost::ssl: create params for ssl cert infos

Was using dynamically scoped variables that won't work with puppet 3.
Created parameters sslcert_* for all certificate fields, changed the
certcn param to sslcert_commonname for consistency and to make existing
recipes fail instead of breaking the configuration.

This change is not backwards compatible and will require fixing code setting
ssl cert values.
Merge pull request #100 from ckaenzig/vhost-ssl-cert-params

apache_c2c::vhost::ssl: create params for ssl cert infos