Rudder

cf-clerk is today responsible of 2 main things:

- reading technique from repos (FS, Git)
- writing promises to the FS from context.

But Rudder is also partially responsible for that second task, as it is the one who knows what should be written, where, with what values.

The current separation of code between Rudder and cf-clerk makes no sense at all.

So for now, move all the promise generation logic into Rudder, so that we could rebuild a coherent whole from that point, and perhaps split-it again in the future from Rudder.

The gain is:
- simplification of actual code ;
- less code (quicker to build) ;
- modification in only one place, so 2 times less pull requests for code related to that.