Whitelist support for 'localhost'

[ChasNelson1990]

First, just wanted to say that this add-on is great, thanks for all your work on it!

I use Jupyter notebooks for my work and occasionally the random profile swaps to OS X or similar and keyboard shortcuts get swooshed around. I thought I could add my localhost to the white list with:
{"url":"locahost"}
but this doesn't seem to work (I've forced a reload of the pages but not restarted firefox). Any suggestions?