Adds KCS-4

[sgerbino]

Resolves #10.

[sgerbino]

All protocol buffer method arguments should be _arguments and all results should be _result. Also, we should add each of these standards to https://github.com/koinos/koinos-proto. I propose we put them in contracts/standard/kcs-*.proto. I did not completely review all of these refactors, simply normalize them so they can be reviewed individually.

[mvandeberg]

The argument proto types mix use of the _args and _arguments suffixes.