Hide the registration code part of the form

* Doesn't disable validation
* Discourages messing with the registration codes

templates/register.html

@@ -11,7 +11,7 @@
             {{ form.username.label }} {{ form.username(size=20) }}
             {{ form.password.label }} {{ form.password() }}
             {{ form.confirm.label }} {{ form.confirm() }}
-            {{ form.registration_code.label }} {{ form.registration_code() }}
+            <input type="hidden" name="registration_code" value="{{ form.registration_code.data }}"/>
             <div class="formSubmit">
                 <input type="submit" value="Register">
             </div>