Replace %20s with nbsps in Chrome

Chrome makes URLs with spaces illegible:
![chrome](http://f.cl.ly/items/2J1N092F420g1z1v3a0l/Screen%20Shot%202013-11-26%20at%2013.14.40.png)

We replace these %20s with nbsps (which look normal) and then parse them as if they were spaces.

Refs #87.