Add jtriley-light theme for light background

Add a jtriley-light theme, which is modified from jtriley to be suitable on light background.

![screen shot 2014-02-20 at 3 24 36 pm](https://f.cloud.github.com/assets/1191434/2215988/17e5c1da-9a00-11e3-95a1-f501de4e3ba4.png)