Bug 11278: Adjusting bulkmarcimport.pl for customization routine and verbose printing

This patch makes two adjustments:
[1] For the verbose option, verbose level 2 now means print the
formatted version of each record.
[2] If a module LocalChanges.pm is found in misc/migration_tools, the
routine "customize" in this module is called for each marc record.
This allows you to make local changes to these marc records before
importing them.

Test plan:
[1] Test the verbose option: a single -v for medium verbosity and two
-v to dump a human-readable version of the record to standard output.
(Do not yet copy LocalChanges.pm in the folder.)
You may used the attached example file on Bugzilla:
perl misc/migration_tools/bulkmarcimport.pl -file zztest01.xml -v -v -b -m XML -t | more
Note the option t for test; no records will be imported.
[2] Copy LocalChanges.pm in the migration_tools folder. You may use the
example provided on Bugzilla (in a patch). If you use the example module,
check the contents of 001, 005 and 590 fields. (The -v -v option allows
you to easily check that.)

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 11278: Followup for customize command line parameter

The initial patch for this bug did not include a specific command line
option for customization. If a module LocalChanges.pm existed, it would
be used without asking.
This patch adds a command line option enabling the customization option
and offering the extra possibility of using another module name. If no file
name is passed, we default to LocalChanges.
Without the -custom option, behavior is as it was.
Also some POD lines are added to document the feature.

Test plan:
[1] Make a LocalChanges.pm in migration_tools. Verify that it is not used,
    if you do not enable the -cust parameter.
[2] Run the script again with -cust. Verify that it is called now.
[3] Copy LocalChanges.pm to Whatever.pm. Make some change. Run with
    -cust Whatever and verify that the new module is used.
[4] Copy Whatever.pm to another dir, make some change. Run with -cust and the
    full name. Verify that the latest change was used.
[5] Run without any option. Check the pod documentation.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 11278: (follow-up) Return an exit value (1) if the module is not found.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>