Closes #195 custom genesis_data

[4gn3s]

Cute Animal Picture

[pipermerriam]

I've now made the appropriate changes to how project configuration works that this can be done in a more sane way. I'd propose doing this via the new project configuration API (which just landed in master and doesn't really have very good documentation). The first idea that comes to mind would involve using a configuration file with a section like the following.

{
  "chains": {
    "my-chain": {
      "geth": {
        "genesis": {
          "difficulty": "0x1",
          ...
        }
      }
    }
  }
}

The Project.get_chain function still allows passing through *args, **kwargs into a chain but looking at the code it looks like I may have broken that API. I'm interested in deprecating that API in favor of moving entirely over to a configuration based approach. Something like allowing you to pass a custom configuration into Project.get_chain that would override the chain configuration in your config file. This could be used for temp chains as well as running one of the pre-configured chains with a slightly different configuration.