Release 3.1.0

• Update copyright year in LICENSE file
• Add API url to Primary Source Sets
• Add apt-show-versions utility to common role
• Add ImageMagick policy.xml file
• Fix column names in munin postgres plugins
• Change thumbp role to support Node.js
• Fix ES port in init script
• Add logrotate configuration for thumbp
• Fix siteproxy wait_for_host port number
• Redirect /wiki to Wayback Machine

Because of the change to thumbp (the frontend's thumbnail proxy), you may
optionally run the thumbp role with the clean_thumbp variable defined, as
follows:

ansible-playbook -u <you> -i development dev_all.yml -t thumbp \
    -e 'clean_thumbp=true'
# ... OR ...
ansible-playbook -u <you> -i ingestion dev_ingestion_all.yml -t thumbp \
    -e 'clean_thumbp=true'

Or, if you like,

ansible-playbook -u <you> -i <whichever> playbooks/thumbp_development.yml \
    -e 'do_deployment=true clean_thumbp=true'

This release contains a security update to fix the ImageMagick exploit
documented at https://imagetragick.com/.