Add default endpoints for RFR, MDB and AB when using ncacn_http transport
Add new parameters to mapi profile for RPC over HTTP

--roh               Use RPC over HTTP (default TLS and proxy port to 443)
--roh-no-tls        Do not use TLS (change default proxy port to 80)
--roh-proxy-port    Set RPC proxy port to use

To tell the dcerpc library if TLS must be used or not, the tls flag
is added to the binding string.