Expose default Michelson contract semantics

[sskeirik]

We can create a standard Michelson contract runner in a similar vein to what tezos-client offers by exposing a slight variation of our semantics. The issue is that standard Michelson contracts do not have enough information contained in them to fully execute the contract. Thus we can either:

1. expose the additional parameters as a file format extension --- similar to what we already do
2. expose the additional parameters as command line arguments --- similar to what tezos-client does