This directory will contain the built sources (iD.js, iD.css)
and images. On a release branch, we will check in the generated
files. For the osm.us/master deploy, it should run make and use
dist/ as the root.
Paths in css are relative, e.g. url(img/foo.png).
It's a drop-in replacement and not seeing any issues with this switch
atm other than ones that were pre-existing - specifically the user shown
in the save dialog sometimes not being present or being out of date, but
the save still being correct.
