realtime.in:  fixup:  run msgd in foreground

(fixup for previous commit)

If `$RTAPI_FOREGROUND` is non-empty, this patch starts `rtapi_msgd` in
foreground daemon mode with output to stdout, but runs in the
background.  After `rtapi_app` is started and other start-up chores
are done, the script waits for `rtapi_msgd` to exit.
fixup for nosetests

- class RunWithLog for starting realtime, logged to file
- class Run for simply firing off commands

fixups:  remove accidentally committed test_050_test.py