ShowHeloOnFocus plugin to use named helper

Updated span to use .jquery_form_help_{name} format and leave helper
spans in dom after fade out. No real need to recreate the dom element
if the user brings that field back into focus.
Domain to lowercase

Convert domain to lowercase for consistency during validation
regardless of user input letter case. name@Example.com breaks
validation.
Merge pull request #29 from HuotMedia/master

Fixed no helper message on focus change