Yesterday, finished converting S3 to use the aws library. Very happy with
the result (no memory leaks! connection caching!), but s3-aws is not merged
into master yet. Waiting on a new release of the aws library so as to not
break Internet Archive S3 support.

Today, spent a few hours adding more tests to `testremote`. The new tests
take a remote, and construct a modified version that is intentionally
unavailable. Then they make sure trying to use it fails in appropriate
ways. This was a very good thing to test; two bugs were immediately found
and fixed.

And that wraps up several weeks of hacking on the core of git-annex's
remotes support, which started with reworking chunking and kind of took
on a life of its own. I plan a release of this new stuff in a week. The
next week will be spent catching up on 117 messages of backlog that
accumulated while I was in deep coding mode.
