[FIX] cleanup of testplan-list

I cleaned testplan listing. Now I no longer generate a list of testplan ids
and get a TestplanInstance resultset of it later but work on the resultset in
the first place. This looks cleaner and makes later changes
easier. Furthermore, testplan instances have both a path and a name but the
filters somehow implied that both are a different word for the same thing. Now
you can filter for both name and path. One testplans that match both
conditions are shown.
What happens, when multiple filters are applied? That was kind of
undefined. Now its clear, all filters beside --id must apply together. --id
overrides all filters beside --active.
[TEST] for testplan-list

This is only a minor test because I only have one testplan in the test
database and haven't found the time to add more to test better.