Fix missing vendor packages

The switch to urfave/cli had a use of a /v2 API, which
go modules handles correctly but vndr ignores. Downgrade
urfave/cli for now until the switch to go modules. Add
missing dependencies, which vndr now sees.
Note that CI was not catching this issue, it seems that
some part of the build process was pulling in dependencies
even if they weren't in vendor, causing the build to work.
However the vendor check was not seeing it. The ARM build
didn't pull in other dependencies into the gopath, causing
those builds to break.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

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

@@ -1,110 +0,0 @@
-package cli
-
-import (
-	"flag"
-	"fmt"
-)
-
-// Generic is a generic parseable type identified by a specific flag
-type Generic interface {
-	Set(value string) error
-	String() string
-}
-
-// GenericFlag is a flag with type Generic
-type GenericFlag struct {
-	Name      string
-	Usage     string
-	EnvVar    string
-	FilePath  string
-	Required  bool
-	Hidden    bool
-	TakesFile bool
-	Value     Generic
-}
-
-// String returns a readable representation of this value
-// (for usage defaults)
-func (f GenericFlag) String() string {
-	return FlagStringer(f)
-}
-
-// GetName returns the name of the flag
-func (f GenericFlag) GetName() string {
-	return f.Name
-}
-
-// IsRequired returns whether or not the flag is required
-func (f GenericFlag) IsRequired() bool {
-	return f.Required
-}
-
-// TakesValue returns true of the flag takes a value, otherwise false
-func (f GenericFlag) TakesValue() bool {
-	return true
-}
-
-// GetUsage returns the usage string for the flag
-func (f GenericFlag) GetUsage() string {
-	return f.Usage
-}
-
-// GetValue returns the flags value as string representation and an empty
-// string if the flag takes no value at all.
-func (f GenericFlag) GetValue() string {
-	if f.Value != nil {
-		return f.Value.String()
-	}
-	return ""
-}
-
-// Apply takes the flagset and calls Set on the generic flag with the value
-// provided by the user for parsing by the flag
-// Ignores parsing errors
-func (f GenericFlag) Apply(set *flag.FlagSet) {
-	_ = f.ApplyWithError(set)
-}
-
-// ApplyWithError takes the flagset and calls Set on the generic flag with the value
-// provided by the user for parsing by the flag
-func (f GenericFlag) ApplyWithError(set *flag.FlagSet) error {
-	val := f.Value
-	if fileEnvVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-		if err := val.Set(fileEnvVal); err != nil {
-			return fmt.Errorf("could not parse %s as value for flag %s: %s", fileEnvVal, f.Name, err)
-		}
-	}
-
-	eachName(f.Name, func(name string) {
-		set.Var(f.Value, name, f.Usage)
-	})
-
-	return nil
-}
-
-// Generic looks up the value of a local GenericFlag, returns
-// nil if not found
-func (c *Context) Generic(name string) interface{} {
-	return lookupGeneric(name, c.flagSet)
-}
-
-// GlobalGeneric looks up the value of a global GenericFlag, returns
-// nil if not found
-func (c *Context) GlobalGeneric(name string) interface{} {
-	if fs := lookupGlobalFlagSet(name, c); fs != nil {
-		return lookupGeneric(name, fs)
-	}
-	return nil
-}
-
-func lookupGeneric(name string, set *flag.FlagSet) interface{} {
-	f := set.Lookup(name)
-	if f != nil {
-		parsed, err := f.Value, error(nil)
-		if err != nil {
-			return nil
-		}
-		return parsed
-	}
-	return nil
-}