Fix for Gingerbread

* 2.3 won't download HTTPS URLs via DownloadManager, so switch to HTTP on <4.0
* trim the 'File:' from the filename

Problems:
* notification disappears after download is complete on Gingerbread
Gingerbread consistency fixes

* force rebuild of gallery data on Gingerbread after download completes
* no auto-opening or persistent notification yet though