feat(cayenne): retrieve single registry by id

Author: hugocortes

lib/Services/cayenne.js

@@ -345,6 +345,15 @@ class Cayenne extends Request {
     return this.send('PUT', path, { payload });
   }
 
+  /**
+   * Retrieves a registry item by its id.
+   * @param {string} registryId
+   */
+  getRegistry(registryId) {
+    const path = `/things/registry/${registryId}`;
+    return this.send('GET', path);
+  }
+
   /**
    * Gets a device properties by hardware id
    * @param {string} hardwareId Device's unique hardware id