Updating govendor dependencies

vendor/github.com/urfave/cli/CHANGELOG.md

vendor/github.com/urfave/cli/LICENSE

vendor/github.com/urfave/cli/README.md

vendor/github.com/urfave/cli/app.go

vendor/github.com/urfave/cli/appveyor.yml

vendor/github.com/urfave/cli/category.go

vendor/github.com/urfave/cli/cli.go

vendor/github.com/urfave/cli/command.go

vendor/github.com/urfave/cli/context.go

vendor/github.com/urfave/cli/errors.go

vendor/github.com/urfave/cli/flag-types.json

vendor/github.com/urfave/cli/flag.go

vendor/github.com/urfave/cli/flag_generated.go

vendor/github.com/urfave/cli/funcs.go

vendor/github.com/urfave/cli/generate-flag-types

vendor/github.com/urfave/cli/help.go

vendor/github.com/urfave/cli/runtests

vendor/vendor.json