Makefile: Re-order the commands in "make release" slightly.

We put verify-version as a dependency, not a recursive action to keep
its output clean, (I know that I will always type "make release"
instead of "make VERSION=X.Y release" so I want a nice, neat
reminder).

Also, put the various ssh-based commands together, and after the
build, (so that it doesn't ask for a password/passphrase both before
and after building).