Manual reload mode

Hi again :)

I've added support for "manual" restart mode. It disables reload and changes gretty's behaviour after "Enter" key pressed: server is restarted instead of being shut down.

This "mode" will be useful if someone (like me :)) wants to manually recompile webapp (e.g. by calling inplaceWebapp task of Gretty plugin) and then restart server.

Old behaviour is kept for current users (reload = 'manual' is required option to activate this feature)