Resolve inability to initiate DCERPC auth session

msf/core/exploit/dcerpc was always setting fake_bind_multi to 1.
This prevented any attempts to initiate the authenticated session.

rex/proto/dcerpc/authentication always expects to receive an auth
type and level, but not all calls made from msf to dcerpc_bind will
be attempting to access dcerpc over TCP with auth. Defaulted
auth_buff generation to use speno/connect when no options are
passed.
Interesting to note that if setting these values in the method
call definition, that passing a NiClass object to the method call
does not result in a value being assigned, but passes the nil to
the array which then gets packed.

At present, wireshark says "DCERPC 451 Bind_ack: call_id: 0,
Fragment: Single, max_xmit: 5840 max_recv: 5840, 1 results:
Acceptance, NTLMSSP_CHALLENGE"