Add the ability to switch from email to ldap and back

webapp/utils/constants.jsx

@@ -185,6 +185,7 @@ export default {
     OFFTOPIC_CHANNEL: 'off-topic',
     GITLAB_SERVICE: 'gitlab',
     GOOGLE_SERVICE: 'google',
+    LDAP_SERVICE: 'ldap',
     EMAIL_SERVICE: 'email',
     SIGNIN_CHANGE: 'signin_change',
     SIGNIN_VERIFIED: 'verified',