Use libravatar image if email address is defined

We use the attribute `emails` (plural) for email addresses with other auth providers like LDAP or SAML. In case of OAuth2 we used the attribute `email` (singular) which resulted in problems.
Furthermore the OAuth2 strategy fell into the default fallback of the provider switch statement. This statement did not check email addresses but did generate the letter-avatar instantly.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

lib/models/user.js

@@ -133,6 +133,10 @@ module.exports = function (sequelize, DataTypes) {
         photo = generateAvatarURL(profile.username, profile.emails[0], bigger)
         break
       default:
+        if (profile.emails && profile.emails.length > 0) {
+          photo = generateAvatarURL(profile.username, profile.emails[0])
+          break
+        }
         photo = generateAvatarURL(profile.username)
         break
     }

lib/web/auth/oauth2/index.js

@@ -62,7 +62,7 @@ function parseProfile (data) {
     id: id || username,
     username: username,
     displayName: displayName,
-    email: email
+    emails: email ? [email] : []
   }
 }