Support for the draft specs

[wetneb]

We should implement the draft specs in the testbench. Ideally it'd be nice to be able to still support 0.1 / 0.2, perhaps even let the user choose which protocol version they want to use (for services which support more than one version)?

[saumier]

@wetneb My team has implemented the latest draft spec that we are calling v0.3 until an official version number is decided. #74

Our version can be tested here:
https://culturecreates.github.io/testbench/

This version checks the manifest of the endpoint to determine the format of request/response. So it should remain compatible with v0.2.

The only UI design change is to optionally display multiple languages returned by the endpoint. Here is the design input:

[fsteeg]

The related PR #74 has been closed, but that's probably just a mistake?