rest-adapter: default options from remoting opts

Modify RestAdapter to use `remotes.options.rest` when no explicit options were specified.

This makes the configuration option `supportedTypes` consistent with other options like `errorHandler` or `json` that are set via `remotes.options.{name}`.

A follow-up for #121 as a part of #118.

/to @raymondfeng please review
/cc @gcirne