[Persistence] Move persistence sources

Move persistence sources into a deeper bundle in preparation for
splitting of persistence into two bundles - one specific to the
Couch adapter, and one for persistence caching generally. This
supports WTD-702, the WARP persistence adapter, which will not
use Couch for persistence but which will want to use the platform-
provided persistence cache.

platform/persistence/couch/src/CouchDocument.js

@@ -0,0 +1,41 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        /**
+         * A CouchDocument describes domain object model in a format
+         * which is easily read-written to CouchDB. This includes
+         * Couch's _id and _rev fields, as well as a sseparate
+         * metadata field which contains a subset of information found
+         * in the model itself (to support search optimization with
+         * CouchDB views.)
+         * @constructor
+         * @param {string} id the id under which to store this mode
+         * @param {object} model the model to store
+         * @param {string} rev the revision to include (or undefined,
+         *        if no revision should be noted for couch)
+         * @param {boolean} whether or not to mark this documnet as
+         *        deleted (see CouchDB docs for _deleted)
+         */
+        function CouchDocument(id, model, rev, markDeleted) {
+            return {
+                "_id": id,
+                "_rev": rev,
+                "_deleted": markDeleted,
+                "metadata": {
+                    "category": "domain object",
+                    "type": model.type,
+                    "owner": "admin",
+                    "name": model.name,
+                    "created": Date.now()
+                },
+                "model": model
+            };
+        }
+
+        return CouchDocument;
+    }
+);