Update README.md

Prepare 0.3.1

Prepare 0.3.0

Update README.md

Remove the newline char at the end

Prepare for 0.2.0

Fix moment().add deprecated issue
Change to write directly instead of emit an event. See #4
Add Android-like logging function signature
Include the stacktrace for trace-level logging
Update test cases
Update README

Improve the performance of the filename formatting

changed to check whether the formatted path needs to be updated instead of formatting the path on every call
prepared for 0.1.5
fixed the typo in README.md
updated test cases for these changes
removed node 0.11 from travis build

Update version in package.json for publish

prepared for 0.1.3

*modified to skip formatting a static path
*replaced moment().valueOf() with new Date()
added test cases to verify those changes
updated README.md, package.json

*Thanks Ryan(https://github.com/rmg) for pushing the high performance
codes!!

prepared for 0.1.2

removed if (string.length > 0)