fix travis tests 4

package.json

@@ -9,7 +9,7 @@
     "babel-preset-stage-3": "^6.17.0",
     "babel-register": "^6.23.0",
     "ethereumjs-testrpc": "^3.0.2",
-    "truffle": "git@github.com:ConsenSys/truffle.git#3.1.9"
+    "truffle": "https://github.com/ConsenSys/truffle.git#3.1.9"
   },
   "scripts": {
     "test": "scripts/test.sh",