Revert validator plugin, fix for poor handling of blocks from the future.

This partially reverts EOSIO/eos#2750 in favor of always loading the producer_plugin again.  Fix for 85b2948e did not link the default plugin properly.  Also check to make sure that we have not received a block from the future when we attempt to start the next block which is the last symptom before whatever caused the crash in EOSIO/eos#2803

cleos support different token precision #2807

Producer pay

- target CPU usage is now 10% rather than 0
- eosio.system now uses "ram" rather than "storage"
- increased max virtual cpu usage to 10000x from 1000x so that 1 staked
EOS is able to transact
- updated bootseq contract with more realistic use case including
      - staking almost all 1B users
      - setting system contract and msig contract
      - allocating resources to staked accounts

- update system contract with setram that properly updates market
pricing

Cleos launches keos in slim branch

Conservative checktime fix for eos #2707

Cleanup coverage report.

Eager checks for the existence of accounts and permissions in actions

cleos get account pretty print, system newaccount

Changes to onerror and improvements to transaction_trace