Proper weights and conversion to fees

In order to get an estimate of the real world transaction fees in Ğ1 and calibrate the quotas, we have to:

• clean up the weight estimation (done in !197 (merged)) (benchmarking, weight sum, remove default Weight::zero(), fix constant weight annotations)
• display the extrinsic weights in user readable way in proportion to the total available amount per block (done in !222 (merged))
• choose non-constant and non-zero weight-to-fee conversion
• (look at runtime upgrade and operational dispatch class to understand overweight problems, see forum)