install-chef-suse: Do not use /tmp, but a directory created with mktemp
Add json-edit utility

This is a small tool that can be used to set the value of an attribute
in json. It will create the parent attributes if needed, and the file if
it doesn't exist.
install-chef-suse: Do not modify data bags from barclamps

Modifying them is quite bad as it means that on updates, either the
change is lost or the changes from the updates are lost.

Instead, we simply create minimal json files with the changes we need,
and we reference them from the crowbar proposal so that they get used.
Remove now unneeded bc-dns-json.rb and bc-provisioner-json.rb tools
install-chef-suse: Allow a minimal crowbar.json

We can configure already the things we want to change compared to the
default crowbar data bag, to allow crowbar.json to be minimal.
install-chef-suse: Mark crowbar user as disabled if not in crowbar.json

If the crowbar user got removed from crowbar.json, then we need to mark
it as disabled so that its presence in the default crowbar data bag can
be ignored.
Use new crowbar-deep-merge-template attribute for incomplete json
Merge pull request #1872 from vuntz/install-chef-suse-rework

Rework how we change default proposals in install-chef-suse