Support GitHub Service Hooks

It would be nice to be able to support github service hooks. I have written this which we have been using for a while:

https://gist.github.com/1296623

If you'd be interested in getting something like this into your tree, that would be awesome. Currently we use it to show commit updates on all of our projects, and its great because its pretty instantaneous. I know you have the same features planned for Announce, so maybe something like this could be integrated into Announce.pm with an option to use postbacks, or poll.

从链接的 GitHub service-hook gist 开始，检查 Announce.pm；issue 将其确定为一个可能的集成点。将所请求的 postback 和 polling 方案与模块的现有行为进行比较，并在修改代码之前定义受支持的 hook 流程和完成标准。

由索引模型根据 Issue 内容生成。