Adds text to clarify current dashboard filter values

Addresses #82 by adding a line of text between the "Workflows" h2 and the table of workflows itself which conforms to pattern:

Workflows on $cluster with status $status and user $user.

$status and $user default to "any".

There may be more elegant ways to work this into the design, but the dropdown menus within the navbar don't look at all good if I include their current value in the text label and dynamically change it when filter value is updated. The resulting shifting of other navbar elements is not so nice.