connect to nreplds:/// URIS from shell using lein nreplds.

according to docs here
https://github.com/technomancy/leiningen/blob/b9dced16d581beaf1657b69ac4d93697e322d83a/doc/PLUGINS.md,
it is hard to shadow current repl command. So I create nrepld command to
connect to nreplds:/// URIS.

I only test it on leiningen 2.4.2.