Implemented the attributes attribute for a 2 ways binding, fixes #8. don't implemented {published} as I think it will only be a duplication of attribute (in fact polymer docs suggests to use attributes instead)
Merge pull request #12 from kentaromiura/adding-attributes-attribute

Implemented the attributes attribute for a 2 ways binding, fixes #8.
Update README.md

Updated the ReadMe to reflect the changes recently done.