Revert "Latest by author can be any type of release."

This reverts commit 2f7df3218c3b60604f5809c596981ddb6233fe25.

Closes #1240
Introduces Perl::Critic (in a very small way).
MetaCPAN::Sitemap now conforms to our Perl::Critic policies.
Skip tests with cpanm installs to help speed travis builds

and assume we don't need to treat JSON.pm specially after 6 months.
Reverse critic test: explicitly exclude old files

instead of having to remember to add new ones
Fix app.psgi to pass critic tests
Merge remote-tracking branch 'upstream/master' into migrate_bootstrap_2_to_3