Have ability to update existing package and resource information from scan results

[JonoYang]

Currently, we do not have a way to update existing package and resource information from the scan results on the scan queue. Given some package or resource data, we should have a function that looks that resource or package up, and then updates fields. Every field but checksums, size, extension, and path are candidates for update. We should also record which scancode-toolkit version the scan results came from in the package history field.

[JonoYang]

We now have logic to reindex Resources and fingerprints for a package. This involves resetting the fields on the scannableURI model, so we request another package scan from scancode.io and then before we process the package scan results, we delete the previous Resources and fingerprints, which are then created again from the scan results.