v0.13.0: Prevent group deletion with installation members (#148)

• Prevent group deletion with installation members
• Lookup private AWS hosted zone domain name (#146)
• Add Https status and write the header in the correct order
• Bump Mattermost operator version to v1.1.0

v0.8.0

Changes:

• Find kops and terraform in the $PATH instead of a hardcoded location
• Add option for AWS RDS installation databases
• Fix kubernetes upgrade issues
• Refactor cluster and installation states and provide report tooling
• Add cluster option to toggle installation scheduling
• Bump mattermost operator to v0.8.0