Start to develop 2.1.0
Remove has method
add setDelimiter method.
Start to develop each method
Add filter method
Add test
Update README
Update README
Change method name getKeys -> keys
Try to fix php on PHP5.3
Try to fix test on PHP5.3
Developing new sort method
Update sort method
Update sort method
Update comments
Update readme
Update README1
Update readme
Add LICENSE file
Merge pull request #4 from kohkimakimoto/2.1.0

develops 2.1.0