Beautifier: Add new class Command and option to format text via piping

The tool's formatting command is now enclosed in Command. For the
formatting itself it can be defined whether to use a temporary file or
the pipe.
Additionally, settings can return the current tool's version - if
needed.

Change-Id: I0e242c3e8016ed77cad92cc97a19fe3384dda858
Reviewed-by: David Schulz <david.schulz@digia.com>