Bug 29515: Make title for HTML customizations optional

Bug 29515: Make title for HTML customizations optional

This adds code to make the title field for HTML customizations optional
while it stays mandatory for news entries.

1) Add a new HTML customization, verify you are forced to enter a title
2) Apply patch
3) Repeat and verify that you can now save without title
4) Add a new news entry
5) Verify that the title field remained mandatory there.

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>