Merge pull request #128 from jinasonlin/master

fix_issue_#102
Bump v0.8.15
Refine with a lot of test cases
Refine test cases
Update test cases
Add shorturl method
Update readme
添加事件分发的API
Bump 0.8.16
Refine testcases
Rename api_customer to api_message
添加List回复内容自定义
Bump 0.8.17
启用加解密功能
Bump 0.8.18
support semantic api
Upgrade urllib
add test
Merge branch 'add-semantic-api' of https://github.com/ifeiteng/wechat into ifeiteng-add-semantic-api
Merge branch 'ifeiteng-add-semantic-api'