Add vert tests

[DenisCarriere]

What's new

• Vert tests ./src/drops.spec.ts
• Ricardian Contracts ./src/drops.contracts.md
• Dummy eosio system contract ./include/eosio.system/eosio.cpp
  • Noop buyram/sellram actions
  • Setup Bancor RAM pool
• Add block_timestamp genesis to state
• Add int64_t bytes_per_drop = 512 to state (exposes bytes consumed as public table instead of private value)
  • replaces record_size field
• #ifdef DEBUG for all src/debug.cpp files
  • Debug flag should be disabled for production mainnet contract

What's changed

• Replaced "wipeall" actions with cleartable action
• Removed init action
• Modified state table to be singleton instead of multi-index with 1 row
• Changed block_timestamp created on drop table
• Change [[eosio::on_notify("*::transfer")]] (to prevent "altcoins" from transferring into repo)
  • add get_first_receiver() contract check for eosio.token