LP#1787479: More layout changes

LP#1787479: More layout changes

Based on cataloger feedback, we 1) Moved the Label Set Configuration higher
grouped with the spine and spine/pocket options because all of these options
are related 2) Moved the starting label option higher because this is the
one setting that will probably be adjusted on each use of the interface and
3) Made the Gap Between Columns setting label conditional on whether the
user us printing to a sheet with label sets or not.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>