ReplyBox: display +1 text next to checkbox

It can be useful to create a simple boolean label:

  [label "Try"]
    function = NoOp
    value =  0 Not attempted
    value = +1 Try to build and run tests

Display the value for +1 in the right side of the ReplyBox
similar to radio button scales which display the meaning of
the currently selected radio button.

Change-Id: Icc3dd6b83bdd4ecd21bfc4eb6d9c8fb232fade39