add json-rpc-engine && eth-json-rpc-middleware to devDependencies

package.json

@@ -155,6 +155,7 @@
     "enzyme": "^2.8.2",
     "eslint-plugin-chai": "0.0.1",
     "eslint-plugin-mocha": "^4.9.0",
+    "eth-json-rpc-middleware": "^1.2.7",
     "fs-promise": "^1.0.0",
     "gulp": "github:gulpjs/gulp#4.0",
     "gulp-if": "^2.0.1",
@@ -169,6 +170,7 @@
     "jsdom": "^8.1.0",
     "jsdom-global": "^1.7.0",
     "jshint-stylish": "~0.1.5",
+    "json-rpc-engine": "^3.0.1",
     "lodash.assign": "^4.0.6",
     "mocha": "^2.4.5",
     "mocha-eslint": "^2.1.1",