Rename "roles" to "units". Put units in their own folders.

lib/units/app/middleware/browser-icons.js

@@ -0,0 +1,12 @@
+var serveStatic = require('serve-static')
+
+var pathutil = require('../../../util/pathutil')
+
+module.exports = function() {
+  return serveStatic(
+    pathutil.root('node_modules/stf-browser-db/dist')
+  , {
+      maxAge: '30d'
+    }
+  )
+}