DocumentsUI: Allow open files instead of URIs

Check files' real path and mime type to open them only in standalone mode.
This allows, for example, installing apks.

Change-Id: I4501c694db84b8595cd3928752254a8914539972
[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: I82ffff5a539448faab8933e2b47591199bf24cb9