CDAP-556 Communication over SSL between AuthServer and LDAP

This allows the enabling of communication between the AuthServer and an LDAP instance over SSL. 

By default, certificate checking is enabled. You can override this property by setting ``ldapsVerifyCertificate`` in the configuration.

Docs will be updated separately.
Because we have a custom login module that is instantiated internally by Jetty, it doesn't have access to ``CConfiguration``. Since it doesn't have access to the configuration, it is set as a static variable here.