This allows the bootstrap of `curl` and `git` on versions of Mac OS X
that cannot reliably download from HTTPS servers any longer. Once these
are both installed users are able to update Homebrew and download files
securely.
Also, as we're doing this, don't point 10.5 users to Tigerbrew as they
are already given caveats for using Homebrew itself.
GitHub now nicely generates a documentation site for us at
http://brew.sh/brew based on our docs folder. Optimise the output of
this and the GitHub docs directory for readability and the various user
groupings.