Simple interface for group policies

[christoph2806]

Proposal:

We need an interface to create policies with arbitrary number of beneficiaries and otherwise identical parameters.

• In the product contract, you should be able to call applyForPolicy with a list of tuples (address, premium) which would then create a single policy but connected to a list of (address, premium) tuples.
• For each address, the premium should be collected,
• In case of a payout, each beneficiary receives a pro-rata amount of the payout.
• There is only a single policy to reduce gas costs
• It should be possible to add more beneficiaries as long as the policy is in theApplied state.
• In case of a very large number of beneficiaries, the payout could be conducted in batches, to prevent reaching the gas limit.

Rationale:

• This could massively reduce gas cost for the typical scenario where we have only a very small number of different risks but for each risk we have a large number of beneficiaries with otherwise identical parameters.
• Adding more beneficiaries should be a very gas efficient process
• Payout in batches would also reduce the gas cost per beneficiary massively.
• For large numbers of beneficiaries, the total gas cost should converge to the gas costs of the token transfer for premium and payout.