Claimable: Batch Create (Day 431)

To make the Claimable project really useful, a batch create function needs to be implemented. Instead of taking a single address, the batchCreate should support an array of addresses as input.

There is no need to specify different cliff and vesting periods, as the most common use case should be simply send out a batch with the same terms. This may increase the cost of gas fees, but it should be way less than doing individually.

One thing I don't yet know is how many addresses can I send in each batch without breaking the smart contract. Does anybody have an idea?