This commit adds a `panicTrace` function to be used as a drop-in
replacement of the `panic` function, with the difference that we
wrap the error in a `WithStacktrace` error, to be later caught
and logged.

This commit makes possible to pass an optional `X-Garg-Error-Scheme`
header in a client request to enable the new error format.

Basically, Gargantext.Prelude exports all of Protolude now.

It can be used to "bolt-on" policy checking into Servant API routes.

We now require CoreNLP listening on port :9000. We will have to find
a way to spin that up in CI as well.

This reverts merge request !166

JSON should now be better so that the UI can handle it in task async
handler.

JSON should now be better so that the UI can handle it in task async
handler.

Still, email is missing and the handling of user click.