Full text search and some other stuff

This MR adds the following stuff:

• Add Full text search
• Add back "Apply Filters" button
• Fix ViewExpiredExceptions from AJAX Requests
• Refine link to post in post-edit
• Fix "Mark duplicate" validation stuff
• Better 404 Exception Stacktraces
• Fix some labels
• Revert upbubbling of Feedback Events in the ReportService
• Add automatic DTO tester (getters and setters automatic testing)
• Add a little bit more coverage

Closes #96 (closed)