treat_symbols_as_metadata_keys_with_true_values doesn't effect example.metadata in around block

If you have `treat_symbols_as_metadata_keys_with_true_values` set and you have
an around hook, the example `Proc`'s metadata won't have keys set as `true`
when passed from the example definition.

I have written a test that demonstrates the problem.

I also fixed a minor typo in a separate commit.