GitHub migration

[Pierre Phaneuf]

So, as some of you noticed, we started migrating the code to GitHub,
as part of an effort to make it as easy as possible to attract
contributions.

From now on, we will be using the GitHub repository here as the system
of record:

https://github.com/google/certificate-transparency

You should be able to switch over your local repositories seamlessly,
by using the following command, assuming that your remote is called
"origin" (which is the default):

git remote set-url origin https://github.com/google/certificate-transparency.git

For now, we have not yet migrated the issues, wiki, and other Google
Code bits and pieces, only the code itself, but we expect to do so
shortly.

We're also doing a round of reorganization in the code repository, in
a sprint-like fashion, as much as possible, to keep the disruption
down. Sorry about that, but hopefully, this will make future work
easier and quicker!

We will also move the RFCs to their own repository (also on GitHub),
which is upcoming. This will let us keep issues with code and RFCs
separately, and avoid having to rebase RFC changes to deal with
unrelated code changes.

So feel free to fork our repository, create a feature branch, and send
pull requests!

[Pierre Phaneuf]

And the RFCs have joined them here:

https://github.com/google/certificate-transparency-rfcs