Bug 15881 - Serials new numbering pattern link should be a toolbar button

Bug 15881 - Serials new numbering pattern link should be a toolbar button

This patch converts the "new numbering pattern" link to a
Bootstrap-styled toolbar button for consistency with other pages in
Koha. This patch also includes minor markup corrections:

- Standardizing on the phrase "Numbering patterns" by eliminating the
  occasional use of "number patterns."
- Removing mistaking closing slash on <select>
- Using standard "Cancel" link instead of a button.
- Adding a colon and space after labels.
- Fixing of "no existing patterns" message.

To test, apply the patch and go to Serials -> Numbering patterns

- Confirm that the "New numbering pattern" button looks correct and
  works correctly.
- Confirm that the entry form looks correct and that the cancel link
  works as expected.

Followed test plan, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com