Remove Bootstrap-default orange background from code elements

Bootstrap colors the background of `<code>` elements light orange by default. Kinda weird: 
![orange](http://f.cl.ly/items/201m0U15151b2f0c273t/Screen%20Shot%202013-05-21%20at%202.08.37%20PM.png "orange")

This pull restores the `background-color` property to good ol' `transparent`: 
![not orange](http://f.cl.ly/items/0O1Q3l2c1t0V1e3i2O1C/Screen%20Shot%202013-05-21%20at%201.58.58%20PM.png "not orange")

This has been blessed by @larz0.