Merge pull request #406 from leonindy/master

add alert summary module, refactor alert module, add weixin sender to all alerts
review code
Merge branch 'master' of github.com:dianping/cat
fix code bug
Merge pull request #407 from youyong205/master

fix bug
move AlertSummaryStringDecorator to test
Merge branch 'master' of https://github.com/dianping/cat