DownloadProvider: Still display as downloading after download failed

When the remaining space is less than 10% of the total space,
download will fail, but it still display as downloading in status bar
after failed in "Downloads" app.

Check error status about downloads. If error exists, will update icon
, content title and content text in notification.

CRs-Fixed: 636489

Change-Id: I5554ef3d1505642c5cd847bd3d2e25a29772dc0d
DownloadProvider: Create and implement DialogDismissListener.

  - Better way to dismiss a host activity then explicitly calling
  getActivity() finish().

Change-Id: I121fb63d2d57c6c4b22abac2389d5c3d5ccad6e4
DownloadProvider: Check if the device actually supports second storage.

Change-Id: I78297ca235e058aecfd0ff5a0e990fc3004b4c77