Use {} for multi-line functions, do/end for procedures

[This article](http://devblog.avdi.org/2011/07/26/the-procedurefunction-block-convention-in-ruby/) highlights an interesting convention for multi-line blocks, and I think it makes code clearer, especially when reading a long block. The braces act as cues -- "Oh, the last expression is going to be used".

I don't really like using `do...end` for one-liners though. Thoughts?
Sure. Should I just make a subdirectory in there for Ruby? `style/samples/ruby/`? I am not comfortable with the idea of using one file for styles and referencing line numbers (as the original guide does), since those will fall out of date.