Vendor in latest urfave/cli

The latest urfave/cli has the ability for us
to use short options when it is a bool.

Signed-off-by: baude <bbaude@redhat.com>

Closes: #100
Approved by: rhatdan

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

@@ -3,6 +3,7 @@ package cli
 import (
 	"errors"
 	"flag"
+	"os"
 	"reflect"
 	"strings"
 	"syscall"
@@ -73,7 +74,7 @@ func (c *Context) IsSet(name string) bool {
 		// change in version 2 to add `IsSet` to the Flag interface to push the
 		// responsibility closer to where the information required to determine
 		// whether a flag is set by non-standard means such as environment
-		// variables is avaliable.
+		// variables is available.
 		//
 		// See https://github.com/urfave/cli/issues/294 for additional discussion
 		flags := c.Command.Flags
@@ -93,18 +94,26 @@ func (c *Context) IsSet(name string) bool {
 					val = val.Elem()
 				}
 
-				envVarValue := val.FieldByName("EnvVar")
-				if !envVarValue.IsValid() {
-					return
+				filePathValue := val.FieldByName("FilePath")
+				if filePathValue.IsValid() {
+					eachName(filePathValue.String(), func(filePath string) {
+						if _, err := os.Stat(filePath); err == nil {
+							c.setFlags[name] = true
+							return
+						}
+					})
 				}
 
-				eachName(envVarValue.String(), func(envVar string) {
-					envVar = strings.TrimSpace(envVar)
-					if _, ok := syscall.Getenv(envVar); ok {
-						c.setFlags[name] = true
-						return
-					}
-				})
+				envVarValue := val.FieldByName("EnvVar")
+				if envVarValue.IsValid() {
+					eachName(envVarValue.String(), func(envVar string) {
+						envVar = strings.TrimSpace(envVar)
+						if _, ok := syscall.Getenv(envVar); ok {
+							c.setFlags[name] = true
+							return
+						}
+					})
+				}
 			})
 		}
 	}