Revert Modified Account Creation Fee

[mvandeberg]

When we added create_account_with_delegation_operation we changed the meaning of the witness voted account creation fee to be the minimum STEEM needed as part of a creation with a delegation. The creation with 100% STEEM is 30x the account creation fee. This change should be reverted for HF 20 so the witness voted account creation fee is the actual fee.

[mvandeberg]

When the hardfork hits, we need to modify the top 20 witness account creation fees by 30 (same effective fee) to prevent creating accounts at an extreme discount. Future witness updates will work as normal.

[mvandeberg]

Other places where the account creation fee is used:

Minimum delegation amounts (should be reduced to match current behavior)
Minimum vesting withdraw amount (removed in #1860)