(PUP-744) Cleanup puppet/ssl require logic

Previously, validator_spec.rb was requiring
'puppet/ssl/configuration', because puppet/ssl.rb did not require
it. Commit 658e4fd34 fixed puppet/ssl.rb, so it is no longer necessary
or desired for validator_spec.rb to require puppet/ssl/configuration.

Also, the default and no_validators were not consistent in expressing
their dependencies on openssl and puppet/ssl.