* Rename functions for DownloadService internal use
* Call DownloadService.start via DownloadManager
* Inline DownloadService.stop into pauseDownloads
* Inline DownloadService.stop into clearQueue
NotificationReceiver will now also stop the DownloadService when
receiving ACTION_CLEAR_DOWNLOADS.
* Provide DownloadService.isRunning via DownloadManager
(cherry picked from commit 86b9262a7ef6c4e97f248bdf417b0e06503fefac)