added composer.json

Hi,

I found your module is very cool but it has one drawback -  I cannot add it to my app using composer (http://getcomposer.org/).
I added composer.json to be ready to submit your module but as you are the author of this module I guess you should submit it instead of me. Here the URL: https://packagist.org/packages/submit 

Could you accept the pull request and submit it please?

P.S.
Happy New Year! :)