add owner_org to dataset from harvest source
Don't set package_index in DatasetHarvesterBase in the gather stage
because the object may be re-instantiated in the fetch stage in
a separate process.
tweak CC0 language following consultation with CC folks and others
incorrect whitespace in indentation, fixes #4
merge - associate harvested datasets to the organization of the harvest source

Merge commit '3f2e11092957fdbf0dbf990b2e9f8d56d1c6ddab'
My fix in 11c5e12c6eb3f9cc7d56564b0bf6536e835cafbd for package_index was pretty bad.
outputting the 'temporal' field was totally messed up (missing return statement, invalid format, etc.)
data.json validation tool at /pod/validate based on upcoming revisions to POD schema
cleanup and compliance for pending POD updates for data.json export
excluded non-dataset packages from the data.json output, like Harvester sources
update data.json output for POD 1.0 spec
update POD validator for 1.0 spec