Remove feedback text from jQuery namespace.

Move the values used for text feedback from jQuery's $.fn namespace into
the defaults object, allowing them to be customized by the user.
Remove resultStyle from the jQuery namespace.

Stop using the jQuery $.fn namespace to store the class name to be
applied to the feedback element. Return it from the testString function
instead.
Remove requirement for username selector.

Make providing a selector for the username field optional. If the
selector is not given, the password value will not be compared to any
username value.
Don't execute on TAB key.

Don't run the password strength test when the user first tabs into the
field. Running the test before they've entered input causes confusion.
Added some demos.

- Basic demo with no configuration.
- Demo of testing with a username combination.
Remove checkRepetition from jQuery namespace.

Took the checkRepetition function definition out of the jQuery $.fn
namespace. It's only used internally so it's better implemented as a
private function inside the closure. jQuery plug-ins should not define
more than one member on $.fn.