Make dojo invites case insensitive as they are email based (#411)

Author: Wardormeur

lib/perm/is-own-invite.js

@@ -17,7 +17,14 @@ function isOwnInvite (args, done) {
       seneca.log.error(seneca.customValidatorLogFormatter('cd-dojos', 'isOwnInvite', err, {userId: userId, inviteId: inviteId, dojoId: dojoId}));
       return done(null, {'allowed': false});
     }
-    isOwn = _.find(dojo.userInvites, {id: inviteId, email: args.user.email});
+    if (dojo.userInvites) {
+      const invites = dojo.userInvites.map((invite) => ({
+        id: invite.id,
+        // Due to dojo saving overwriting invites, the email may be null
+        email: invite.email ? invite.email.toLowerCase() : '',
+      }));
+      isOwn = _.find(invites, { id: inviteId, email: args.user.email.toLowerCase() });
+    }
     isOwn = !_.isEmpty(isOwn)? true: false;
     return done(null, {'allowed': isOwn});
   });