Lowercase usernames on authentication about django-cas-ng

[mingchen]

If you would like to send a pull request with new option to convert username that would be great.

[nitmir]

Note that this can also be resolve by telling the CAS to use a particular field as username (for instance, the field username in your database) and not the name entered by the user on login. For instance:

                <property name="resultAttributeMapping">
                        <map>
                                <entry key="aid" value="aid" />
                                <entry key="uid" value="user" />
                […]
                    <bean class="org.jasig.cas.services.RegisteredServiceImpl">
                        <property name="id" value="4" />
                        <property name="name" value="Intranet 2" />
                        <property name="description" value="L'intranet 2 du Cr@ns" />
                        <property name="serviceId" value="https://intranet2.crans.org/**" />
                        <property name="evaluationOrder" value="4" />
                        <property name="usernameAttribute" value="user" />
                        <property name="allowedAttributes">
                            <list>
                                <value>login_mail</value>
                                <value>prenom</value>
                                <value>nom</value>
                                <value>cn</value>
                                <value>user</value>
                            </list>
                        </property>
                    </bean>

Here the CAS will transmit as username the value of user witch is the value of uid in our ldap database, where the case is enforced.