Fix Numerous Bugs

speculative fix for issue #2994

Added automake as a dependency

- signature checks are skipped while replaying
- abi of eosio.system contract was inconsistant, Fix #2999
- reduced console spam while syncing and replaying
- add max usage of resources when querying account

send_deferred_transaction : new parameter "replace_existing"

Update Docker's config.ini to use Dawn4 history_api_plugin

Add creation of new keys via the wallet

This change adds the concept of a wallet being asked to create a new private/public key pair. It is a precursor to hardware key support in the wallet because hardware key stores don’t always have the concept of “importing” a key. It’s also beneficial as it gives an alternative means to `cleos create key` which if not careful can cause a private key to easily weasel its way in to a user’s shell history.

Make the default key added to each wallet optional

By default we add the "root" eosio key to each created wallet. This key is configurable, however it also is always required. Change to code to accept an empty key which is an indicator that no key shall be added to created wallets.

Orginally did this because it makes an incoming unit test a little easier; but I can also see why some users may not way a key placed in every single wallet they create too.

Reorder Resources

ubuntu: fixed issue #2973

Fix reflect issue in block_header.hpp

Add branch argument to Dockerfile [skip-ci]

Merge slim into master

Add null check with exception expected by net_plugin