Add lastUpdate column to documents which stores the last update in milliseconds

package.json

@@ -71,7 +71,7 @@
         "c9.ide.language.javascript.infer": "#b9c2e4bdb8",
         "c9.ide.language.jsonalyzer": "#a0549e14ff",
         "c9.ide.language.codeintel": "#4e0a272229",
-        "c9.ide.collab": "#e316906fc4",
+        "c9.ide.collab": "#7b8de939e4",
         "c9.ide.local": "#9169fec157",
         "c9.ide.find": "#e632ecf4be",
         "c9.ide.find.infiles": "#4484d6162d",