请更新Guide和README

[yunyuecoder]

如果出现以下情况：
The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.

1.去安装一下CocoaPods，并到XWalkView目录下（Podfile文件）执行Pod install

如出现一下XXXXXX/xwalk-sample/crosswalk-ios/XWalkView/XWalkView/XWalkWebView.m:8:9: 'GCDWebServer/GCDWebServer.h' file not found
2.In File -> Add Files to "Echo"（你的项目）..., choose the Pods.xcodeproj from crosswalk-ios/XWalkView/Pods/Pods.xcodeproj;

同时建议Guide加入git版本号和项目版本区分。

[halton]

@jondong is working on that, should be updated after Chinese National holiday.