Calculate weights or create weight functions.  #21

The weight system in substrate/FRAME is key to preventing resource exhaustion attacks on the chain, so it is important to set sane values for weights.

Specifically, weights in https://github.com/playproject-io/datdot-substrate/blob/master/pallet-datdot/src/lib.rs are currently all placeholder values.

Some resources - https://www.shawntabrizi.com/substrate/substrate-weight-and-fees/