DownloadProvider: Transfer speeds in notification

Change-Id: Ic7efcdfe7a329946f3b63c331064ac2f16faafeb
DownloadProvider: Normal notification for singles

This builds upon the previous DownloadNotifier, but changes
the notification style when downloading single files by
removing the big view.

Change-Id: I06d2b555bb51613661ccb50df3b7bc59439b2252
DownloadProvider: Standardize notifications

Standardize play store and browser download notifications
Image: http://i.imgur.com/w3VaRUK.png

Change-Id: Ibadcca3725b4adb330a5670414ac8f89790448b8
DownloadProvider: Clear notifications for deleted items

Clear notifications for Deleted items from Download list

Issue: Notifications for deleted items from the Download
list are not getting cleared and thus tapping on such
notifications causes crash (Illegal Argument Exception)

Fix: clear notifications for deleted items by adding them
in the stale list

Change-Id: I74e94ccca7ca79ec421d76023c5c894d9487e185
DownloadProvider: Properly open images

Open images with content://media/ instead of
content://downloads/ URI.

This allows images to be shared directly after opening them with the
DownloadManager.

Change-Id: I3648b1c563acaa80b28a230bdb43ead3476cf3e7
DownloadProvider: Creates parent directories before creates file

Change-Id: I4b61c1aeb8054397fa2a2f162b068e683c7e9635
DownloadProvider: Remove download notification after preview

Removes download notification from the notification bar after
previewing it. There should be an additional check for download
shown in the notifications after completion to prevent from
situation when ContentObserver is unregistered and the onChange
is never called

Change-Id: I339c08152caf53342cf17e34c46e187fdad5a4c0