Adopt module description links

Problem/Motivation

Currently the drupal module description links are outdated

Steps to reproduce

https://www.drupal.org/project/pdf_reader →

Unter the info "The implemented PDF renderers are:" all the links are outdated and not available an more
http://docs.google.com/viewer
http://mozilla.github.com/pdf.js -> mybe the correct one https://mozilla.github.io/pdf.js/ or https://github.com/mozilla/pdf.js
https://viewer.zoho.com/home.do

Proposed resolution

remove links or find working links :)