Add Ubuntu 18.04 Build/Test and timeouts

Fix/ram usage checks

Created forked test

Slim branch code coverage fixes

Add additional test for non-priviledged account sending scheduled transaction

remove utf 8 api

Fix to a bug in tester destruction and changes to transaction_metadata to fix wasm_tests

by default do not compress the packed_transactions created when passing a signed_transaction into transaction_metadata because that breaks assumptions made in the tests

It is possible to pass an optional `packed_compression_type` field to
the `transaction_metadata` constructor to override this default
behavior.

This change now fixes the tests dealing with network usage in wasm_tests
(all of wasm_tests now passes).

- udpate system contract to set initial account bw to 0
- update system contract to process new on block header
- update cleos api and get info api

add abi_serializer support for shared_ptr and now reflect failed_dtrx_trace field in transaction_trace