Give an =encoding to all POD.

Supposedly, this will fix a problem that MetaCPAN had while processing
the last release of Pinto.  For reasons unknown to me, the last release
never showed up on MetaCPAN and all links to it returned 404.
Reformat recent change log entries to comply with CPAN::Changes::Spec.

If the change log follows this format, MetaCPAN will make it look pretty.