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

I can not connect to my nreplds:/// URI using `lein repl :connect nreplds:///..... ` because your lein-nreplds does not work.

When I look at the code, It is not the way the leiningen plugin code should be, so I try to make it myself.

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 nreplds command to connect to nreplds:/// URIS.

You can run it like 

`lein nreplds :connect nreplds:///absolute-path-to-unix-domain-socket`

I only test it in leiningen version 2.4.2.

what it does is running `leiningen.repl/repl` but skipping `leiningen.repl/ensure-port` execution because at my current test environment (leiningen 2.4.2), leiningen requires that host has port. It's just a ugly hack, but I need to make sure that I can make the plugin. 

I'm still looking a way to make this plugin works on all leiningen version 2>.

What do you think?