Further protection against 5.6.2 in t/metafile_data.t
Armour remaining tests against 5.6.2
Make _add_requirements_to_meta_* use a ref not listify hash
Use constant for default meta-spec info
Use constants to eliminate repetition in t/metafile_data.t
Specify 2.0 for META.json
Make $mm->metafile_data return hashref
Internal metadata now in 2.0 format
Make test code prettier
sprintf <<TAG bad, replaced with 'TAG'