Merge pull request #1 from natural-law/master

Modify the project implement
Merge pull request #2 from natural-law/master

Add game developer guide document
Merge pull request #3 from natural-law/master

Add IAP protocol and implement on android
Merge pull request #4 from natural-law/master

Adjust the interface of ProtocolIAP
Merge pull request #5 from natural-law/master

Implement plugin alipay & add sample HelloIAP as IAP plugin demo
Merge pull request #6 from natural-law/master

Add introduction of plugin-x directory structure.
Merge pull request #7 from natural-law/master

Modify the implement of plugin alipay
Merge pull request #8 from natural-law/master

Optimize document & implement plugin CMGC