QtIFW

Rewrite the isRunning implementation and remove private class.

Use a more descriptive enum name. On Windows keep the lower case
version of the process name instead of calling toLower() several
times. Print a warning if we cannot obtain or release the lock.

Change-Id: Iaaefae0359cd214290f62ce78677cb343da8823c
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>