Documentation updates

Fix a few glaring typos/omissions.  Add docs for requires_rt and
rt_too_new.
Switch from warning to dying

We should refuse to install harder when your RT is too hold.
Work around loading RT::Handle loading the config.

Calling require RT::Handle; executes FinalizeDatabaseType which calls
RT->Config->Get('DatabaseType').  On 3.8 this errors because the config
isn't loaded.  On 4.0 and 4.2 this transparently loads the config.

Loading your config requires a user who can read RT_SiteConfig.pm which
means that you would be required to run perl Makefile.PL as root.

Instead, dummy up Config just enough to get RT::Handle loaded so we can call
cmp_versions.  If anything later calls RT::LoadConfig; our shenanigans
will be wiped clean.
Prep for 0.32_1 dev release