Switch to using jq to write out initial JSON
Switch to using jq to write out initial JSON

Rather than having a frankly horrible python one-liner to write out
the initial JSON in devtest_testenv, switch to using jq with a
heredoc. Much readable.

Change-Id: I475fa35236144ca93c8668a83f62f4ac546883d0

rdo-management/tripleo,rdo-management/tripleo