Observe initial namespace for nREPL session

[Marko Topolnik]

Recently a leiningen pull request was accepted which makes the nREPL server start with the current namespace set according to the configuration in project.clj. Apparently nrepl.el ignores the current namespace at the server side and explicitly sets it to user upon connect. It would be nice if nrepl.el could be brought to respect this initial namespace binding.