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.
Does it make sense to have a test case that does not set `ldapsVerifyCertificate` to make sure cert verification happens?