chore(package): update mocha to version 3.0.0 (#157)

fix(devDependency)
https://greenkeeper.io/
diff --git a/package.json b/package.json
index f4b16b5..3bd8046 100644
--- a/package.json
+++ b/package.json
@@ -43,7 +43,7 @@
     "fs.extra": "^1.3.2",
     "istanbul": "^0.4.3",
     "marked-man": "~0.1.5",
-    "mocha": "^2.5.3"
+    "mocha": "^3.0.0"
   },
   "engines": {
     "node": ">=0.8.0"