This adds a checksum in the gitian build script to make sure that
ossl tool and theuni's patch matches what is expected. Also changes
the url to use https and adds the same instructions to the release docs.
Instead of re-naming the tarballs used for the code signing step to the generically
named tarball that is used, keep the versioned naming. Only copy them to the
correct filename when they are needed at build time.
TheCharlatan