Resolves: fdo#69925 Wiki Publisher Extension is not working

Regression from http://cgit.freedesktop.org/libreoffice/core/commit/?id=b80d8c695e6b6ded231e67ed9a80bcd1f1250c03
"compareTo" has been replaced by "==", so we compared the equality ot the pointers on the objects instead of the content of the strings
To make it simple and since we compare String objects, let's simply use "equals" method

Change-Id: I65bc1a87751297411fdbe722d3f49bce5e291638