Standard Account Contract

[hwwhww]

What is wrong?

Subtask of #203
Goal: All accounts are contracts. Contracts can pay for gas, and users are free to define their own security model.

• There's a Serpent example code by Vitalik. Update it to Viper LLL version:
  https://github.com/ethereum/EIPs/blob/bd136e662fca4154787b44cded8d2a29b993be66/EIPS/abstraction.md#rationale
• Validation code for abstraction

How can it be fixed

• Add Vyper LLL Contract and utils: Standard user account #230
• Test (depending on Implement CREATE2 opcode #224, Add PAYGAS opcode #234 )

[hwwhww]

@jannikluhn I updated the ticket description, feel free to modify it.