v0.8.1

Changelog

• 3ab7b36: Update version numbers: 0.8.0 (@dev-errant)
• a682c7a: cluster: updates for kind 1.13 (#223) (@nicks)
• 76a5efa: cmd: add "ctlptl delete --cascade=true" to delete the registry attached to a cluster. (#221) (@nicks)
• 374d528: cmd: normalize cluster name. (#222) (@nicks)