Issue #29: open the app in 2 steps

Updated unique file name to include origin ip address.
Modifed post reponse to return created url to redirect.
Created optional parameter to behave in the old way: to make redirect immediatelly (?redirect=[non-null]).
Restored removed demo scripts (from git history). Added new code to support post requests from js.
Made a few more demos to show & test new ways to open app (added option to use remote server address in demo code).
Updated demo to allow to use server prefix (to test with 2 different servers).
Added CORS support to the server.
Updated version: 0.0.25.

Demo page (start-app-demo-post.html):

Demo page

lilliputten / sankey-graph-app