[1/2] Base: DownloadManager: add support pause/resume/stop notifications

Add pause, resume and stop functions to make user can pause, resume and stop downloads by manual in downloads application.

Change-Id: I0050bb588d2f8414d00ad7e5a73d6f620ded60fb
Merge "[1/2] Base: DownloadManager: add support pause/resume/stop notifications" into kitkat