Bug 16381: Fix capitalization on tags review page

Bug 16381: Fix capitalization on tags review page

- Fixes capitalization of the sub heading "Displaying ... terms"
- Fixes button label of "Test"

To test:
- Look at all, approved, rejected, pending tags and check
  the line below the heading "Tags" - "Displaying..."
- Check a term using the search box on the left side
  Before the patch: Test - Processing... - test
  After the patch this should be Test again in the end.

Capitalization looks good. QA tools complain about tabs, but there
are loads of tabs all over review.tt. Proper formatting of the whole file
could be done in a separate bug.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>