Remove 'pre' tag from watch result to allow scrolling

Surrounding the code and results in a `pre` forces the results to appear on one line and doesn't allow you to scroll the result. This removes the `pre` tag and lets the default styles for `.result-mark` take over.
The watch result will now be a maximum of 50% of the parent height.
I also added a small amount of spacing between each watch.

Old
![screen shot 2014-03-08 at 3 10 39 pm](https://f.cloud.github.com/assets/185091/2364486/12480f1a-a678-11e3-9aba-c932647ea475.png)

New
![screen shot 2014-03-08 at 3 05 08 pm](https://f.cloud.github.com/assets/185091/2364480/f43acefe-a677-11e3-8e05-bec3ee3df48f.png)

@bfabry