Add Esperanto to the list of languages

The translation dashboard is showing 98% translated in Esperanto.
https://translate.openstack.org/iteration/view/horizon/stable-queens

Change-Id: Ib509cc9023666ef6d0f3dd6cd1880c7904f9fde2

openstack_dashboard/settings.py

@@ -222,6 +222,7 @@ LANGUAGES = (
     ('en', 'English'),
     ('en-au', 'Australian English'),
     ('en-gb', 'British English'),
+    ('eo', 'Esperanto'),
     ('es', 'Spanish'),
     ('fr', 'French'),
     ('id', 'Indonesian'),