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

lib/units/storage/plugins/image/task/get.js

@@ -0,0 +1,20 @@
+var util = require('util')
+var http = require('http')
+var url = require('url')
+
+var Promise = require('bluebird')
+
+module.exports = function(path, options) {
+  return new Promise(function(resolve, reject) {
+    http.get(url.resolve(options.storageUrl, path))
+      .on('response', function(res) {
+        if (res.statusCode !== 200) {
+          reject(new Error(util.format('HTTP %d', res.statusCode)))
+        }
+        else {
+          resolve(res)
+        }
+      })
+      .on('error', reject)
+  })
+}