Bug 14997: Remove C4::Dates from tools (import / export)

Bug 14997: Remove C4::Dates from tools (import / export)

This patch removes C4::Dates from:

- tools/export.pl
- tools/import_borrowers.pl

Note: For testing, both need preparation without patch, see below.

To test export:
- Without patch applied, go to
  Home > Tools > Export data > Export bibliographic records
- Define Start date / End date for Accession dates
- Export bibliographic records as 'without-patch.mrc'

- Do the same with patch, export as 'with-patch.mrc
- Compare the files, they should be the same

To test Import patrons:
- Without patch
- Go to Home > Tools > Import patrons
- Create a patron category like 'TEST' (useful for filtering...)
- Prepare a file with some patrons with category TEST to import.
  Fill date of birth, enrolment date, expiry date with values
  formatted in syspref format, in iso format and garbage
- Import
- Review the imported patrons (search for category TEST)

- With patch: Change cardnumber and names in import file
- Import
- Review again and compare with results from previous import.

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>