play nicer with bundles that use mvp args

The documentation says:

    NOTE: If you overwrite mvp_multivalue_args you'll need to include the
    value of plugin_remover_attribute (-remove by default) if you want to
    retain this functionality. As always, patches and suggestions are welcome.

We can avoid having to do this in the composing class by using a method
modifier, with a fallback method (to wrap in case the class doesn't define
one) that returns nothing.
Test that mvp_multivalue_args merges properly
Comment on how the sub modification works
Remove obsolete docs about mvp_multivalue_args
Use .mailmap to normalize committer email addresses
Generate github README in pod instead of markdown
Document change (and credit ether) in the changelog
v0.102

  - Use 'around' (and an empty sub) to add attribute name to
    mvp_multivalue_args.  Thanks to Karen Etheridge for the patch!