launch_daemon: Added basic ability to stop/start jobs via API.

* Stopping a job is very simplistic right now, and will have to be
  extended considerably, probably with its own job.

headers/private/app/LaunchDaemonDefs.h

@@ -26,6 +26,8 @@ namespace BPrivate {
 enum {
 	B_GET_LAUNCH_DATA			= 'lnda',
 	B_LAUNCH_TARGET				= 'lntg',
+	B_LAUNCH_JOB				= 'lnjo',
+	B_STOP_LAUNCH_JOB			= 'lnsj',
 	B_LAUNCH_SESSION			= 'lnse',
 	B_REGISTER_SESSION_DAEMON	= 'lnrs',
 	B_REGISTER_LAUNCH_EVENT		= 'lnre',

headers/private/app/LaunchRoster.h

@@ -34,6 +34,9 @@ public:
 									const BMessage* data = NULL,
 									const char* baseName = NULL);
 
+			status_t			Start(const char* name);
+			status_t			Stop(const char* name, bool force = false);
+
 			status_t			StartSession(const char* login);
 
 			status_t			RegisterEvent(const BMessenger& source,
@@ -56,6 +59,9 @@ private:
 	friend class Private;
 
 			void				_InitMessenger();
+			status_t			_SendRequest(BMessage& request);
+			status_t			_SendRequest(BMessage& request,
+									BMessage& reply);
 			status_t			_UpdateEvent(uint32 what,
 									const BMessenger& source, const char* name,
 									uint32 flags = 0);