go mod

Module maintenance. More information: https://golang.org/cmd/go/#hdr-Module_maintenance.

• Initialize new module in current directory:
  go mod init {{moduleName}}
• Download modules to local cache:
  go mod download
• Add missing and remove unused modules:
  go mod tidy
• Verify dependencies have expected content:
  go mod verify
• Copy sources of all dependencies into the vendor directory:
  go mod vendor