[binding-http] improve basic authentication support

After working on #292 I noticed that the TD specs describe different methods to configure Basic authentication schema. In particular, [BasicSecurityScheme](https://www.w3.org/TR/wot-thing-description/#basicsecurityscheme) has the `in` field where one can configure the location of the encoded `username` and `password`. Currently, node-wot only supports the default: header. We should support also `query`, `body`, and `cookie`.