Adapted configuration for making Autodiscover works with Outlook Anywhere

Avoid creation of RPC/Proxy autocertificate
Remove useless autodiscover certificate as superseeded by subjAltName in Domain cert
Download the CA cert in RPC/Proxy model
Migrate RPC Proxy certificate to new use our zentyal-ca
Notify when OpenChange is using the domain certificate
Some minor improvements in help messages

+ Public methods doc
Remove warning on revoking a certificate
Adapted to latest layout
Adapted to required the version with Autodiscover + HTTPS OA