Tentative support for primary-system-name.

OK, new tentative patch for https://github.com/quicklisp/quicklisp-controller/issues/7
that supersedes https://github.com/quicklisp/quicklisp-controller/pull/8

There was an infinite loop because I was calling normalize-dependency on dependencies before the system definition was properly initialized. That was bad. This version accumulates dependencies, then normalizes at the end. Should work better. Once, again, untested (except this time I checked that it compiles.)