Fix test failed in old version of ruby

DESC: B
1. Before ruby 2.0.0, String.chars return an Enumerable object, not an
array, and it causes "uniq" method not found error.
Use old hash format to support old version of ruby

DESC: B
Use old hash format to support old version of ruby

DESC: B
Use old hash method index instead of key to support old version of ruby

DESC: B
Use old hash method index instead of key to support old version of ruby

DESC: B
Add doc

DESC: A
Add gem, travis, coveralls badges in README

DESC: A
Release 1.0.0

DESC: RS