Allow tool install instructions to be Markdown

:fork_and_knife: Tool install instructions will now be rendered as Markdown. Since this could potentially become rather lengthy and truncating Markdown won't work so well this removes the install instructions from the tool partial. Also auto_link tool descriptions with the help of rinku.

![screen shot 2014-08-06 at 3 50 40 pm](https://cloud.githubusercontent.com/assets/316507/3833030/03f99d78-1da3-11e4-8604-4efe19acb790.png)