npm install before running test server

Author: Lukas Schmidt

.travis.yml

@@ -3,4 +3,8 @@ xcode_project: Socket.IO-Client-Swift.xcodeproj # path to your xcodeproj folder
 xcode_scheme: SocketIO-iOS
 osx_image: xcode7
 script: xcodebuild -project Socket.IO-Client-Swift.xcodeproj -scheme SocketIO-iOS -sdk iphonesimulator build test  CODE_SIGN_IDENTITY="" CODE_SIGNING_REQUIRED=NO
-before_install: node Socket.IO-Test-Server/main.js
+before_install: cd Socket.IO-Test-Server/ && npm install
+install: node Socket.IO-Test-Server/main.js
+cache:
+  directories:
+    - Socket.IO-Test-Server/node_modules