Default field value to '' if undef from null DB value
Add debug messages to 1.1.1 upgrade for scrip deletes

Previously the 1.1.1 upgrade printed an error message when
scrips to be deleted were not found. Add debug messages to make
it clearer that the upgrade script is deleting scrips in that
phase and it's OK if the scrips to be deleted are not found.
Remove requirement for RTFM in 1.9.0 upgrade script

RTIR 3 will require some version of RT4 which now includes RTFM
in core as Articles, so the RTFM is no longer required.
Convert RTFM updates to RT::Articles updates
Add a make upgrade-database command

This makes use of Module::Install::RTx's make-upgrade branch as well as
RT's 4.0/customize-upgrade-wordings.
Use the built-in-logger

Printing to stderr without newlines gets you really horrible
run-together warnings.  RT 4 forces rt-setup-database to log anything
warn or higher to the console, so just use the logger.
Merge branch '2.9/make-upgrade-database' into 2.9-trunk
Merge branch '2.9/1.1.1-upgrade-script-updates' into 2.9-trunk
Merge branch '2.9/dont-require-rtfm-for-1.9.0-upgrade' into 2.9-trunk