Changes from previous:
[Changes for 0.29 2011-05-20]
* add requires_rt to handle requiring an RT version
since MakeMaker and Module::Install::AutoInstall can't deal
with RT version numbers.
[Changes for 0.28 2011-03-15]
* search /opt/rt4 for RT.pm
[Changes for 0.27 2010-12-16]
* Include RT's lib/ directory in INC so that requires()
on RT::VERSION work properly
[Changes for 0.26 2010-12-14]
* Search RTHOME before searching @INC
This works around distribution packages lurking in @INC
340671cf37