Bug 12417: adding the units tests of the module Koha::Borrower::Files.pm

Bug 12417: adding the units tests of the module Koha::Borrower::Files.pm

The module Koha::Borrower::Files.pm was not tested

To test:
1/ Execute the command: prove t/db_dependent/Borrower_Files.t
2/ The command has to print:
t/db_dependent/Borrower_Files.t .. ok
All tests successful.
Files=1, Tests=23,  2 wallclock secs ( 0.04 usr  0.01 sys +  1.47 cusr  0.08 csys =  1.60 CPU)
Result: PASS

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Squashed patches.
Now test pass
No koha-qa errors

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>