[Templates] fallback overloading in Template::Exception

[Mark Fowler]

Fallback on Template::Exception's overloading wasn't turned on, so doing
something as simple as:

  if ($exception ne "Problem")
  {
    ...
  }

Caused all kinds of problems.  I've patched the code (and tests) to DTRT
now.

Mark.

-- 
#!/usr/bin/perl -T
use strict;
use warnings;
print q{Mark Fowler, mark@twoshortplanks.com, http://twoshortplanks.com/};