tighten up entries
remove unnecessary plugin
now using [Git::Contributors]
Dist::Conflicts may be buggy? report its version
add some keywords to metadata
ensure that diagnostics are printed with the right encoding
report all installed JSON backends, and which one is being used

I'm seeing lots of cpantesters reports like this:
http://www.cpantesters.org/cpan/report/6b1588ca-b9a6-11e3-aa24-b5c0dfbfc7aa

indicating something, somewhere, is misbehaving, but we don't have enough
information yet to figure out what.
also dump information about what YAML backend is in use
this file has been dead since 2007!
whitespace
make key order consistent in tests
patched to handle serialization of undef params.

(modified from original patch in github pull request #6)
test that unset attributes are not serialized, but set-and-undefined attributes are
changelog for PR#6
also report the version of MXRP, since MooseX::Storage::Deferred has special logic for it