This patch adds the misc/cronjobs/overdue_notices.pl script that is intended to replace
overduenotices.pl, overduenotices-30.pl and overduenotices-csv.pl. It adds messages to
the message_queue to be sent later (by process_message_queue.pl). It also marks borrowers
as debarred if their issues become too overdue.

It is intended to be run from cron nightly with usage something like:
0 2 * * * misc/cronjobs/overdue_notices.pl

C4::Members:
 - improved documentation on ModMember
 - made ModMember return a useful value (the return value of the database call)
 - added a DebarMember method
 - adding t/lib/KohaTest/Members/DebarMember.pm to test ModMember

misc/cronjobs/overdue_notices.pl
 - designed to replace overduenotices.pl, overduenotices-30.pl, and overduenotice-csv

Changes to C4::Letters:
 - EnqueueLetter now lets you pass in to_address and from_address which can override defaults
 - _send_message_by_email pays attention to these defaults.
 - now handles attachments with MIME::Lite

C4::Overdues
 - added GetBranchcodesWithOverdueRules
   - added t/lib/KohaTest/Overdues/GerBranchcodesWithOverdueRules.pm to test that.

circ/overdue.pl
 - replaced call to obsolete overduenotices-csv.pl with call to overdue_notices.pl

KohaTest:
 - added three helper methods: random_phone, random_email, random_ip
   - these can be used to populate example records
 - you can now pass an optional lengh to random_string

Signed-off-by: Joshua Ferraro <jmf@liblime.com>