Attach mask plugin to a password field instead of a text field

Hi @coderguy,

Thanks for the plugin! This was the only "showpassword" plugin I found which can use a jquery element as a toggler. I needed this feature because we have two password forms in our page, and I wanted the togglers to act independently:

    $(".js-toggleable-password").each(function(index, element){
      $(element).mask(toggle: $(element).next('js-password-toggler'));
    });
      
I modified the plugin so that it attaches the unmasked text field to a password field, and not the other way around. I found that submitting a password through a text field can be insecure. For example, it's possible for the submitted password to appear in the html if the password field's form is sent back to the user for changes.

I don't know if you need this change, but here it is, with tests and all.

Thanks,

George