Fix release-qualify script.
Fix release-qualify script.

Turns out that robot does not save json file and logs in the same
directory. We have to assume that release qualification directories are
the one starting with rc-test.

For all the directories that have the long-run-test.json/log files:
- Check json file
- Check stress failures
For all the rc-tests* directories
- Extract tar if any but do not fail as some file may not have nginx
  directory
- Check for the presence of error.log, if not fail
- Filter out known errors

Change-Id: I96444e9b5bd073dddaaac6ae588af5c07e74d807

cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp