Fix shell output.

lib/roles/device/plugins/shell.js

@@ -42,7 +42,7 @@ module.exports = syrup.serial()
           function endListener() {
             push.send([
               channel
-            , reply.okay()
+            , reply.okay(null)
             ])
             resolver.resolve()
           }
@@ -55,6 +55,8 @@ module.exports = syrup.serial()
             stream.end()
           }
 
+          stream.setEncoding('utf8')
+
           stream.on('readable', readableListener)
           stream.on('end', endListener)
           stream.on('error', errorListener)

lib/wire/util.js

@@ -45,7 +45,7 @@ var wireutil = {
           source
         , seq++
         , true
-        , data || 'success'
+        , data === null ? null : (data || 'success')
         , body ? JSON.stringify(body) : null
         ))
       }