Provide Sync Helper for Re-Import of existing Products

[nkuehn]

To create import / backend integrations that also update existing products it is necessary to calculate the differences and create a set of update actions.

There should be a helper in the SDK analogous to this one in the Node SDK: https://github.com/sphereio/sphere-node-sdk/blob/master/src/coffee/sync/product-sync.coffee

It would be very helpful if the scope of the sync would be controllable (e.g. not automatically assuming everything should be synced). Optional goodie would be white / blacklisting product attributes.

[hajoeichler]

This should be definitely go into the backend to avoid coping this diff calculation + action creation logic into all programming languages/SDKs.

[nkuehn]

I added this here because it's not near to realization on the platform roadmap and the need really hurts - probably because the whole import endpoints thing looks like it will take a longer conceptual discussion to become really good. If the platform is faster we can still close this proposal.

[b3nl]

+1