*8880* Use user.username as label for username field in password change form

The field "username" in the one-step password change form (/templates/user/loginChangePassword.tpl) is using the "user.login" key as label  instead of "user.username".

In English this is not a problem as "user.login" is replaced by the term "Login" and is understandable.

However in other languages, such as Brazilian Portuguese, "user.login" is translated to terms that do not apply. In Portuguese, for instance, it is translated to "Acesso" wich does not make any sense to a Brazilian for asking the user's username.