Fix RT::Template->Create to return failure message if requested when called.

Manifests itself in the following error upgrading from rt-3.6.11 to rt-4.0.18:

[critical]: The 'message' parameter (undef) to Log::Dispatch::Output::log was an 'undef', which is not one of the allowed types: scalar
 at /usr/lib/perl5/site_perl/5.8.8/Params/ValidatePP.pm line 634
	Params::Validate::__ANON__('The \'message\' parameter (undef) to Log::Dispatch::Output::l...') called at /usr/lib/perl5/site_perl/5.8.8/Params/ValidatePP.pm line 485
	Params::Validate::_validate_one_param('undef', 'HASH(0x109ddae0)', 'HASH(0x109ed380)', 'The \'message\' parameter (undef)') called at /usr/lib/perl5/site_perl/5.8.8/Params/ValidatePP.pm line 345
	Params::Validate::validate('ARRAY(0xe57f0f0)', 'HASH(0xe5fa000)') called at /usr/lib/perl5/site_perl/5.8.8/Log/Dispatch/Output.pm line 39
	Log::Dispatch::Output::log('undef', 'level', 'error', 'name', 'screen', 'message', 'undef') called at /usr/lib/perl5/site_perl/5.8.8/Log/Dispatch.pm line 214
	Log::Dispatch::_log_to('Log::Dispatch=HASH(0xe587980)', 'level', 'error', 'name', 'screen', 'message', 'undef') called at /usr/lib/perl5/site_perl/5.8.8/Log/Dispatch.pm line 167
	Log::Dispatch::_log_to_outputs('Log::Dispatch=HASH(0xe587980)', 'level', 'error', 'message', 'undef') called at /usr/lib/perl5/site_perl/5.8.8/Log/Dispatch.pm line 145
	Log::Dispatch::log('Log::Dispatch=HASH(0xe587980)', 'level', 'error', 'message', 'undef') called at /usr/lib/perl5/site_perl/5.8.8/Log/Dispatch.pm line 42
	Log::Dispatch::__ANON__('Log::Dispatch=HASH(0xe587980)', 'undef') called at /app/int-rt-stage/sbin/../lib/RT/Handle.pm line 1034
	RT::Handle::InsertData('RT::Handle=HASH(0xdd73600)', './etc/upgrade/3.7.10/content', 'undef') called at /app/int-rt-stage/sbin/rt-setup-database line 298
	main::action_insert('datafile', 'undef', 'datadir', './etc/upgrade/3.7.10', 'backcompat', 'ARRAY(0xb988e20)', 'force', 1, 'package', ...) called at /app/int-rt-stage/sbin/rt-setup-database line 404