Added a more robust email regex.

Previous regex would match with an @ symbol and no domain extention. 

ie. s@s, would be treated as a valid email addess. 
You can test this on the validate.js website.

This fix ensures that a domain extension is applied. 
I can not take credit for the regex pattern, it was found on StackOverflow here: http://stackoverflow.com/questions/46155/validate-email-address-in-javascript