Ancestor Issues

In case the Ancestor Table of Confluence gets corrupted, which occurs now an then, our calculation of the Ancestor Properties fails.

We should provide an alternative approach so that we can calculate the ancestors 'manually' in case the Ancestor API of Confluence returns the empty list.

'Manually' refers to the strategy not to fetch all ancestors by a single request, but following the path to the root of the page tree, one parent page at a time. This alternative strategy is only applied in case the ancestor request yields no result.