Very productive & long day today, spent adding a new feature to the 
webapp: Internet Archive support!

[[!img /assistant/iaitem.png]]

git-annex already supported using archive.org via its S3 special remotes,
so this is just a nice UI around that.

How does it decide which files to publish on archive.org? Well,
the item has a unique name, which is based on the description
field. Any files located in a directory with that name will be uploaded
to that item. (This is done via a new preferred content expression I added.)

So, you can have one repository with multiple IA items attached, and
sort files between them however you like.
I plan to make a screencast eventually demoing that. 

Another interesting use case, once the Android webapp is done, would be add
a repository on the DCIM directory, set the archive.org repository to
prefer all content, and *bam*, you have a phone or tablet that
auto-publishes and archives every picture it takes.

Another nice little feature added today is that whenever a file is uploaded
to the Internet Archive, its public url is automatically recorded, same
as if you'd ran `git annex addurl`. So any users who can clone your
repository can download the files from archive.org, without needing any
login or password info. This makes the Internet Archive a nice way to
publish the large files associated with a public git repository.
