Added birthday.coffee (delegate your birthday greetings to Hubot).

This script allows you to delegate you birthday greetings, celebrations and quotes to Hubot.

It supports the following commands:

*   hubot birthday quote for \<user\> -- congratulate \<user\> with a random birthday quote
*   hubot celebrate me \<user\> -- congratulate \<user\> with an inspirational greeting 
*   hubot happy birthday me \<user\> -- congratulate \<user\> with a humorous greeting