Make show-password-js work for change password too

The show password js depends on the password field to have
an id of "password". So give it a proper id.

Also fixed the label generation for the case of field.name
and field.id being different.

mediagoblin/edit/forms.py

@@ -64,7 +64,8 @@ class EditAccountForm(wtforms.Form):
     new_password = wtforms.PasswordField(
         _('New password'),
         [wtforms.validators.Required(),
-         wtforms.validators.Length(min=6, max=30)])
+         wtforms.validators.Length(min=6, max=30)],
+        id="password")
 
 
 class EditAttachmentsForm(wtforms.Form):