Return error when interfaces go missing.

This should close sidorares/node-dbus#43

This fixes a crash when trying to get an interface which does not exist.
Merge pull request #44 from Scypho/bug/dissapearing_objects

Return error when interfaces go missing.
0.1.1
handshake: throw error when no authentication methods left
handshake: only send one nul byte
handshake: log error on unsupported auth method
Merge pull request #46 from gfxmonk/handshake

Fix a number of issues in handshake code
prefix unmarshalled vatiant with signature. fixes #45
fix unmarshalling
assign correctly variant values to message fields #45
handshake: take a copy of defaultAuthMethods before mutating
implement a no-op removeListener for proxies

This is just to prevent an error when callers expect to be able to
both add/remove a listener (e.g stratifiedJS events module)
add support for direct dbus communication (pass {direct:true} to createClient)
Merge pull request #47 from gfxmonk/direct-connection

Support for direct connections
Added opts to systemBus so that one can override user id