Copy theme command - resolves #247

Added copy-theme command.
Not creating curly brace delimited code blocks for `for`, `if`, etc is against our house style, on the basis that it often leads to bugs down the line as changes are made to the code. The only place where we do it within BRJS is for single line `throw` statements (for the sake of readability), since there can be lots of them at the beginning of a method, for example:

```
if(!app.dirExists()) throw new NodeDoesNotExistException(app, this);
```