License checkbox for part 2 or part 3

Depending on which license is picked, the appropriate checkbox needs
to be checked. Currently the checkbox for these fields accepts:
'Yes' & 'no' (not 'No' as it was set to currently).
Cleaner way to diff PDFs

Previously two defendants were populated into the PDF, which would
add a continuation sheet. Which in turn would be considered as a
creation of a new PDF document. PDFs contain a timestamp when they
were created, so when diff-ing two PDFs, they could never be the
same just for this reason.

The workarounds for it were dirty, so thats why I'm testing the
population of a PDF without a continuation. Then the continuation
is being tested if it has the correct number of pages.
Merge pull request #101 from ministryofjustice/67559684/explicit-licence-negation

License checkbox for part 2 or part 3