Fix minor atest formatting issues. Separated these changes from PR #1776
Merge pull request #1787 from guykisel/atest-minor-fixes

Fix minor atest formatting issues. Separated these changes from PR #1776
Process: Convert args to strings also with Jython on Linux.

Process uses custom encode_to_system with Jython on Linux due to
non-ASCII problems. Now arguments are converted to strings (issue
Merge branch 'master' of https://github.com/robotframework/robotframework