Refactor tests to stop sharing global models between different test
suites and use local per-app model registry instead.
Also clean up all test code to use `const` and `let` instead of `var`.
Allow remote-connector users to provide "options" property in the
datasource configuration, this "options" object is then passed down to
RemoteObjects and allows e.g. configuration of pass-through
authorization, where the remoting connector passes the access token
used to make the incoming request down to the backend service invoked.
Miroslav Bajtoš
Agnes Lin
Kenny Sabir
Miroslav Bajtoš
Ryan Graham
Geoffroy