Idiomacy pass

@andymoe - continued cleanup, incorporating most comments from previous review.
 
If the class extension changes are acceptable, my intention is to apply this style uniformly to the rest of the code base.
Hey @cnatoli do you think perhaps we should use NSUInteger for length throughout these interfaces since we use length primarily with `[NSData dataWithBytes:bytes length:length]` and this method takes NSUInteger... Thoughts? Might have to examine each implementation a bit more closely to look for possible casting/truncation issues.