Fully automate generating examples from TypeScript to JavaScript

@egekorkan mentioned the following in PR https://github.com/eclipse/thingweb.node-wot/pull/178#issuecomment-595154554

> Couldn't be sure where to put this information but instead of doing this removal of 3-4 lines in Travis, I think it would be better to have a postbuild script that gets triggered by npm once the npm run build is finished. This way, it would be easier to develop new examples and not need to push them to GitHub to trigger the Travis script. However, it must be made sure that this script runs on WIndows and Linux systems, which probably means a node.js script

Start by running npm run build and reading the existing Travis configuration and example-generation flow. Confirm where the npm postbuild hook is configured, then verify that the completed build generates the expected JavaScript examples on both Windows and Linux.

Written by the indexing model from the issue text.