Integrated customizable bash prompt

Get a nice configurable shell prompt for all nodes... YEAH!
This is a followup pull request after discussion on https://github.com/crowbar/barclamp-deployer/pull/219
> But it's more correct than the old version out of the perspective of valid json formatting. Sure, specification said you can escape but you don't have to... But it strongly depends on the JSON implementation.

Err. Link? Details? I'm not aware of this being required by JSON.

> Edit: Who needs to copy&paste a hashed password seriously from this json?

I took the password example; but look at your diff, and you'll see plenty of changes where slashes got escaped. That's really the whole thing that I'm opposing to.