Expose more request configuration

[spluxx]

The http client implementation that we're using is node-fetch.

A good start for this feature would be to

1. Add a field that holds a list of (config name, value) to the model request_builder.ts.
2. Create a tab for configuration next to the expected message
3. Create Action/Reducer to link up the view / storage
4. Include those options on request.ts - either pre-fetch, during fetch, or post-fetch.

We can start with simple ones available from node-fetch:

• follow
• compress