Merge branch 'development' into swift3

* development:
  change travis config
  remove log for dorequest

.travis.yml

@@ -5,12 +5,9 @@ branches:
 xcode_project: Socket.IO-Client-Swift.xcodeproj # path to your xcodeproj folder
 xcode_scheme: SocketIO-iOS
 osx_image: xcode7.3
-before_install:
-    - cd Socket.IO-Test-Server/
-    - npm install
-    - cd ..
+branches:
+  only:
+    - master
+    - development
 install: node Socket.IO-Test-Server/main.js &
 script: xctool -project Socket.IO-Client-Swift.xcodeproj -scheme SocketIO-Mac build test -parallelize
-cache:
-  directories:
-    - Socket.IO-Test-Server/node_modules

Source/SocketEnginePollable.swift

@@ -102,7 +102,6 @@ extension SocketEnginePollable {
     
     func doRequest(for req: URLRequest, callbackWith callback: (Data?, URLResponse?, NSError?) -> Void) {
         if !polling || closed || invalidated || fastUpgrade {
-            DefaultSocketLogger.Logger.error("Tried to do polling request when not supposed to", type: "SocketEnginePolling")
             return
         }