fix test dependency versions

Author: bencmbrook

package.json

@@ -31,10 +31,10 @@
   },
   "homepage": "https://github.com/fiznool/passport-oauth2-refresh",
   "devDependencies": {
-    "chai": "*",
-    "mocha": "*",
-    "sinon": "*",
-    "sinon-chai": "*"
+    "chai": "^3.4.1",
+    "mocha": "^2.3.4",
+    "sinon": "^1.17.2",
+    "sinon-chai": "^2.8.0"
   },
   "engines": {
     "node": ">=0.10.0"