Allow uuid() to be called statically.

static/cosmopolite.js

@@ -674,6 +674,13 @@ Cosmopolite.prototype.uuid = function() {
 };
 
 
+/**
+ * @see https://www.cosmopolite.org/reference#uuid
+ * @return {string}
+ */
+Cosmopolite.uuid = Cosmopolite.prototype.uuid;
+
+
 /**
  * Build a new Promise object with exception handling.
  *