#659: Allow filtering report tables by label

[broeder-xceptance]

See: #659

This branch also includes some minor additional fixes for the report tables:

• Clearing a filter input using the clear icon now also clears the filter value in the hash.
• The terms "asc" and "desc" in the sorting setting of the hash were flipped. They are used correctly now.
• The sorting hash didn't update when clicking next to the filter input in a table header. This is fixed now.
• Overview tables (e.g. on the Requests page) are no longer hidden based on the filter input.