UserAccount model: Username and Email properties should have a 254 character StringLength annotation.

As per [RFC 5321] [1] and verified technical [errata] [2], the maximum length of a valid email address is 254 characters. Additional discussion can be found on [Stack Overflow] [3]

The StringLength data annotations for the Username and Email properties of the UserAccount model have been updated to reflect this. 

[1]: http://tools.ietf.org/html/rfc5321#section-4.5.3
[2]: http://www.rfc-editor.org/errata_search.php?rfc=3696&eid=1690
[3]: http://stackoverflow.com/questions/386294/what-is-the-maximum-length-of-a-valid-email-address