Update Source URL for various packages

The following source URLs have been updated:

  - Nagios
  - libpng
  - zlib
  - gd

This PR also includes a patch for cacerts to copy the cacerts.pem directly from the cache.

Jenkins build: http://andra.ci.opscode.us/job/private-chef-trigger-ad-hoc/38/

Jenkins Run successful: http://andra.ci.opscode.us/job/private-chef-test/85/build_os=ubuntu-10.04,machine_architecture=x86_64,project=private-chef,role=tester/console