Use Newlines around multi-line blocks

Style update - add newlines around multi-line blocks.

I've seen this done a lot on many projects, but noticed it missing from this repo.

Example:

Before:
```
#...
pandas = Pandas.all
pandas.each do |panda|
  panda.tickle
  panda.output.should eq "Hee hee!"
end
pandas.feed_bamboo
```

```
#...
pandas = Pandas.all

pandas.each do |panda|
  panda.tickle
  panda.output.should eq "Hee hee!"
end

pandas.feed_bamboo
```