As suggested in #2780 this PR redirects all stderr on a perl level
to stdout so that we should see all errors which we miss because
we can't redirect (>/dev/null in check) or we haven't redirected yet.
Also old checks are imporved, so that $prg is used as in newer
checks.
Often in the past travis was hitting a limit (50min?).
This is a try to make reasonable cuts to the unit tests:
- For STARTTLS some checks with OPenSSL are skipped
- For JSON and HTML outputs --ids-friendly was added assumming we
don't change the output of ticketbleed, CCSI, HeartBleed and ROBOT any more.
- There's also not point to run those checks against badssl
- for the diff check we switch to 'or diag' to display a dfifference
* die statement if testssl.sh cannot be found from the current path
* comment everything out for JSON
* don't repeat the pattern, use a variable
* use "speaking" variable names
