Remove the libraries in /app/js/ and rely on packages instead

[tanius]

These libraries are probably (hopefully) legacy items that have been added in an earlier version, while newer versions are used via a package manager. For example, bower install installed jquery 3.2.1, so it should be avoidable to have /app/js/jquery-1.12.4.js.

If some of these libraries are still in use, we should find packages in the NPM repositories to provide the same libraries via npm install, and then remove them. They are not part of this project's source code, so they should not be in this repository.