Merge pull request #25 from Unknwon/master

Fixed bug: repeat build in Mac OS, change to check file ModTime instead of event time
fix post data format
add test
Merge pull request #26 from fanngyuan/master

add test
刚才漏了
Merge pull request #27 from fanngyuan/master

刚才漏了,不好意思
avoid panic when len(log) == 0 in colorLog func