Updated outdated links to new addresses which provide the same content

This change is unobstrusive and does not delete anything - just makes references
accesible again.
Delete references to the Pylons Cookbook, which doesn't exist anymore

No suitable replacement could be found for the the links.
Change the reference to the Wiki tutorial from the TG Book

Apparently, the deprecated directory still contains a copy of the
Wiki tutorial.
CGI explanation from Wikipedia
Finally just delete Gone-Away-Links...
Merge pull request #27 from moschlar/linkcheck-master

Fix broken links in the 2.2 docs