June Change Proposal: Minimization

I would propose we tighten up the minimization language and add examples.  In particular, I would change "reasonably necessary" to "strictly necessary," and add these examples:
> Allowed Example: A third-party advertising network uses a minimal set of deidentified data to frequency cap advertisements.
> 
> Disallowed Example: A third-party analytics service generates public reports about aggregate page impressions. It retains full protocol logs for two weeks, even though it has no need for them.