20467 - mcollective service does not gracefully exit on windows

In the past MCollective didn't not exit cleanly on Windows when run as a
service.

This commit refactors the WindowsDaemon to correctly use the #running?
method in win32 to exit instead of calling exit.
Merge pull request #122 from ploubser/bug/master/20467

20467 - mcollective service does not gracefully exit on windows