New rewrite of provider. By moving to promises we should no longer have issues with double-quits.

lib/util/procutil.js

@@ -34,3 +34,28 @@ module.exports.fork = function() {
     })
   })
 }
+
+// Export
+module.exports.gracefullyKill = function(proc, timeout) {
+  function killer(signal) {
+    var deferred = Promise.defer()
+
+    function onExit() {
+      deferred.resolve()
+    }
+
+    proc.once('exit', onExit)
+    proc.kill(signal)
+
+    return deferred.promise.finally(function() {
+      proc.removeListener('exit', onExit)
+    })
+  }
+
+  return killer('SIGTERM')
+    .timeout(timeout)
+    .catch(function() {
+      return killer('SIGKILL')
+        .timeout(timeout)
+    })
+}