ESC to close modals

Replaces #46 

I rebased on top of the dev branch - can someone take one last quick look? Many thanks!

@azirbel @jcollins1991 @charlescharles 

Should the files in ```dist/``` be included here? I noticed that running grunt messes around with all sorts of files and folders that are not in ```.gitignore```.
Well said. I don't have a strong opinion on which of the two is better but I see why the computed makes sense and I'm ok with going with that.