Combine filters on steps page

[mikaelsvensson]

It is possible to filter the list of people base on group memberships or custom attributes. However, the GUI does not show that only the last changed filter drop-down will be used when filtering (even if other filter drop-downs have also been set).

Acceptance criteria:

• The different filtering options can be combined
• ...or only one drop-down is shown and it contains all filtering options.