[sugar] [RELEASE] Read 50

[Morgan Collett]

I've released Read-50, available at:

http://dev.laptop.org/pub/sugar/sources/read-activity/Read-50.tar.bz2
http://dev.laptop.org/~morgan/bundles/Read-50.xo

This release fixes a number of issues with Read which were all related
to saving in the datastore, including:

* #7948: Shared Read activity does not share PDF file.
* #7168: Can't open shared document
* #6488: "keep"ing a read session throws an error; need a way to bookmark
* #7091: no preview thumbnail in Journal for PDFs in Read activity

There are also updated translations for ja and pt.

Regards
Morgan