Use serialization for snapshots

[kddnewton]

This gets rid of the LANG issue and makes it so that we don't have to deal with encoding problems.

To get the nicer snapshot diffs, run:

git config diff.snapshot.textconv bin/deserialize
git config diff.snapshot.binary true

[jemmaissroff]

One small thing we could do is make a helper script to get nicer git diffs. But since it's only two lines, definitely don't think that's necessary

[kddnewton]

Yeah I was thinking it might be good to have a bin/setup script for installing dependencies and other stuff. We could add this stuff to that.

[eregon]

This means it's no longer possible to review the snapshots diff on GitHub.
What's this LANG issue? Wouldn't it be enough to dump the snapshots as UTF-8 or binary to solve the issue?