[fix] remove unused pipe in subprocess

For some reason this seems to be triggering a leak of a open file
descriptor, even though it should be garbage collected.

As for why it's there...well there was a time when I had hoped of
implementing support for stdin.

nrm/containers.py

@@ -248,7 +248,7 @@ class DummyRuntime(ContainerRuntime):
 
     def execute(self, container_uuid, args, environ):
         import tornado.process as process
-        return process.Subprocess(args, stdin=process.Subprocess.STREAM,
+        return process.Subprocess(args,
                                   stdout=process.Subprocess.STREAM,
                                   stderr=process.Subprocess.STREAM,
                                   env=environ)

nrm/subprograms.py

@@ -118,7 +118,7 @@ class NodeOSClient(object):
                for envname, envval in environ.items()]
         cmd += " env:'"+" ".join(env)+"'"
         args.append(cmd)
-        return process.Subprocess(args, stdin=process.Subprocess.STREAM,
+        return process.Subprocess(args,
                                   stdout=process.Subprocess.STREAM,
                                   stderr=process.Subprocess.STREAM)