Fix load message tests

This fixes the failing `load_more_messages.js` tests, the issues were basically way too short timeouts and issues with the page-reloading. To resolve the page-reloading-issues I added an optional `padName` attribute to `helper.newPad()` which allows you to set the name of the pad that is going to be loaded. If no `padName` is given a random name will be chosen (as it has always been).