Bug 33512: Change text and add button classes on serial-edit page

Bug 33512: Change text and add button classes on serial-edit page

To test:
1. Create a subscription
2. Make sure that you choose "Create an item record" when receiving the serial and associate it with a record.
3. Fill out the numbering pattern stuff and save the subscription.
4. Receive and change the status to arrived. Doing so will make the item subfields appear for editing.
5. Add some stuff, like a barcode, and Save.
6. Now, if you have made a mistake, you may want to edit the serial/item. Check the edit box and click 'Edit serials '
7. For your issue that has already arrived click 'Click to add item'. The item record from before appears.
8. Apply patch.
9. Try 6 & 7 again. The existing items should now read 'Click to edit item'

Signed-off-by: Andrew Auld <andrew.auld@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>