consolidate all post-parse metadata checks

consolidate all post-parse metadata checks

This puts all of the needed post parsing checks on the metadata into a
single method that is used by all parsing methods (.txt, JSON, XML, YAML).
This provides the single place to normalize the internal representation of
the metadata.

It would be good to also change the internal representation to use more Python
bool/int types so that less post parsing is needed for JSON, XML, and YAML.

The SMSSecure test .pickle was changed to account for the use of lstrip()
and rstrip() on all 'script' types.

This also changes the example JSON to use ints for versionCodes