LP#1642337: more tweaks to the patch series

LP#1642337: more tweaks to the patch series

This patch makes the following changes:

- ensures that the Boolean values get saved as 't' or 'f', as
  the reporter builder doesn't recognize JSON true or false in
  this context.
- pretty-prints the current filter value in the dialog
- removes a logging line

To test
-------
[1] Apply the patch.
[2] Create or clone one or more report templates and add Boolean
    column filters. Change the filter value and verify that
    it displays the current value and lets you change it.
[3] Run reports from the template(s) created in step 2 and
    verify that the reports produce the expected results.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Signed-off-by: Dawn Dale <ddale@georgialibraries.org>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>