Merge pull request #2 from vladgolubev/master

Move async from devDeps to deps

package.json

@@ -38,7 +38,6 @@
   },
   "homepage": "https://github.com/ben-ng/mutex-js#readme",
   "devDependencies": {
-    "async": "^1.5.2",
     "benchmark": "^2.0.0",
     "doctoc": "^0.15.0",
     "jstrace-bars": "^1.2.3",
@@ -47,6 +46,7 @@
     "tap": "^5.1.1"
   },
   "dependencies": {
+    "async": "^1.5.2",
     "bluebird": "^2.9.34",
     "conflux": "^1.1.3",
     "defined": "^1.0.0",