Bug 16917 - Error when importing patrons, Column 'checkprevcheckout' cannot be null

Bug 16917 - Error when importing patrons, Column 'checkprevcheckout' cannot be null

Error:
DBIx::Class::Storage::DBI::_dbh_execute(): Column 'checkprevcheckout'
cannot be null at C4/Members.pm line 697

Test Plan:
1) Attempt to import a patron via csv
2) Note the error
3) Apply this patch
4) Repeat the import
5) No error!

NOTE: Given that all the other tests ran (comment #2), except
      those in comment #3, I resorted to following the test plan
      above using the attachment provided in comment #5. I
      believe the issues in comment #3 constitute other bugs
      which need fixing and are unrelated this bug. Applying the
      patch does resolve the error triggered, and the code is
      good.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>