Ensure correct formatting of CLI examples.

These examples currently render with spaces removed at line breaks, which caused me some confusion when copy-pasting.  :smiley:

*NB: This does not happen in development, presumably due to differences in rendering of markdown.*

![screen shot 2014-09-05 at 7 30 08 pm](https://cloud.githubusercontent.com/assets/11674/4173107/af523388-3554-11e4-8060-ee8aad2f5b55.png)

Instead, I rendered them as code blocks like the example for windows.  It seemed to turn out well and one can now copy-paste without issue.

![screen shot 2014-09-05 at 7 31 30 pm](https://cloud.githubusercontent.com/assets/11674/4173111/c8b3c9fe-3554-11e4-940f-54e30d8ca0f1.png)