Generate a simpler test case than add11

[s1na]

The EVM EE fails to produce the correct post state root for the default test case (add11), and therefore I had to disable the evm test in CI (#32). Passing add11 is a longer term task (highlighted requirements in #33). Before that we should nevertheless craft a few test cases manually and work our way up to add11. Initially we should avoid gas handling & SSTORE in the test cases to make things easier.

Similar to state tests the test cases should have a two pre accounts with balances and one with a bytecode. The bytecode should end with the RETURN statement, e.g. it should ADD two numbers and then RETURN the result. We also send along the expected return value as input to EE and the EE after executing bytecode checks the return value against expected value. It should also correctly perform the value transfer from sender to the contract.