no need for a huge stack trace when plugin :version checks fail

Before:

    Dist::Zilla::Plugin::Test::MinimumVersion version (2.000002) not match required version: 2.000003 at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Dist/Zilla/Util.pm line 101, <GEN1> line 70.
            Dist::Zilla::Util::_assert_loaded_class_version_ok('Dist::Zilla::Util', 'Dist::Zilla::Plugin::Test::MinimumVersion', 2.000003) called at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Dist/Zilla/MVP/Section.pm line 29
    ... 234523423 line snipped...

after:
    Dist::Zilla::Plugin::GatherDir does not define $Dist::Zilla::Plugin::GatherDir::VERSION--version check failed at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Dist/Zilla/Plugin/Git/GatherDir.pm line 18, <GEN1> line 8.
    BEGIN failed--compilation aborted at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Dist/Zilla/Plugin/Git/GatherDir.pm line 18, <GEN1> line 8.
    Compilation failed in require at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Module/Runtime.pm line 317, <GEN1> line 8. at /Users/ether/perl5/perlbrew/perls/perl-5.16.2/lib/site_perl/5.16.2/Config/MVP/Assembler.pm line 62.