Auctions can start in the future

[kevinbeauregard]

Currently, All auctions start when they are created.

In the future, we will want to create auctions that start at a predefined time / block.

This is useful for the sale of NFTs or of tokens which have very little or no liquidity (and thus would not expect a public rate change prior to StartTime / StartBlock

Additionally, if we wish to use actual time rather than blocks, then we should enable an endTime parameter as well.