json-edit: Allow using stdin/stdout as json input

With this change we can use json-edit (instead of sed) inside the various
smoketest/modify-json scripts that smoketest calls.
smoketest: Add (very simple) distro detection

This should be enough to avoid doing the same test in the barclamps'
smoke testing scripts.
smoketest: Provide an install_package function

To handle the different package installation commands on the various
supported distros.
install-chef-suse: install smoketest tools when using --from-git
Merge pull request #1926 from rhafer/feature/roxy-smoketest-on-sles

Initial work to make the smoketest work on SLES based installs