Update Pod-Parser to CPAN version 1.51

Update Pod-Parser to CPAN version 1.51

  [DELTA]

  25-Jan-2012           Marek Rouchal                        <marekr@cpan.org>
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  Version 1.51
  + CPAN#74271: Pod::Parser should not flag L<text|hyperlink>
    undo change CPAN#47473: L<alt text|URL> _is_ allowed (see discussion on
    pod-people and p5p); confirmed by blead change; references:
    http://code.activestate.com/lists/perl-pod-people/1690/
    http://code.activestate.com/lists/perl-pod-people/1393/
    http://perl5.git.perl.org/perl.git/commit/f6e963e4dd62b8e3c01b31f4a4dd57e47e104997
  + bump all module versions (except Pod::PlainText) to 1.51
  + update META.yml (thanks rjbs for the hint)