Allow dot as a valid character in an selinux identity name

Both of these are legal: unconfined_u and unconfined.u

https://pagure.io/freeipa/issue/7510

Signed-off-by: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>

ipatests/test_xmlrpc/test_selinuxusermap_plugin.py

@@ -620,9 +620,11 @@ class test_selinuxusermap(Declarative):
             command=(
                 'selinuxusermap_add', [rule1], dict(ipaselinuxuser=u'bad+user')
             ),
-            expected=errors.ValidationError(name='selinuxuser',
-                error=u'Invalid SELinux user name, only a-Z and _ are allowed'
-                ),
+            expected=errors.ValidationError(
+                name='selinuxuser',
+                error=u'Invalid SELinux user name, only a-Z, _ '
+                      'and . are allowed'
+            ),
         ),