Implement destroy command

I have implemented rails-like `destroy` command that removes code generated by `generate` command.
How about this for that function where `moduleName` is the `dasherizedModuleName`?

```javascript
Blueprint.prototype.mapFile = function(file, moduleName) {
  file = Blueprint.renamedFiles[file] || file;
  return file.replace('__name__', moduleName);
};
```