Update middleman to 4.1.10
There are performance issues according to https://forum.middlemanapp.com/t/performance-middleman-4-vs-middleman-3
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
There are performance issues according to https://forum.middlemanapp.com/t/performance-middleman-4-vs-middleman-3