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: I0914a680f08eb96949b56e08719eb28d2e80ccc9
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: I65c79923b7aef4c1113e572030c9c7f750b73df0
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: I7a27d19fff994876eee07d4c4d63b2808cc516d3
CRs-Fixed: 536562
DownloadProvider: don't allow backups.

Change-Id: I5a07244d4bb7e11af4f5eb1a624fc20165248aab
Creates parent directories before creates file

Change-Id: I124f7ce2b731b100e9572d7c5d95206e243ee316
Signed-off-by: Roger Chen <cxr514033970@gmail.com>
Add Download Speeds in notification

This commit adds the ability to show the current total download
speed in the expanded mode. This is applicable to both single
and multi file downloads.

Screenshots:
Multi  - http://i.imgur.com/3t7yAy7.png
Single - http://i.imgur.com/MMqmA22.png

Slim'ed by mnazim

PS
- move strings to slim_strings

Change-Id: I801dbe61c7ee59d0c1d14d5851ad6dc3a7678499