etcdctl/command: mk command with Create

- This attempts to fix #3676.
- The previous pull request (#3679) was
  trying to change the interface so that it can be executed with TTL flags.
- Since `Create` is just a simple wrapper of `Set`, there is no need changing
  the interface, which means we need to remove the TTL flags from `mk` command.

/cc @yichengq

etcdctl/command/mk_command.go

@@ -17,7 +17,6 @@ package command
 import (
 	"errors"
 	"os"
-	"time"
 
 	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/codegangsta/cli"
 	"github.com/coreos/etcd/client"
@@ -28,9 +27,6 @@ func NewMakeCommand() cli.Command {
 	return cli.Command{
 		Name:  "mk",
 		Usage: "make a new key with a given value",
-		Flags: []cli.Flag{
-			cli.IntFlag{Name: "ttl", Value: 0, Usage: "key time-to-live"},
-		},
 		Action: func(c *cli.Context) {
 			mkCommandFunc(c, mustNewKeyAPI(c))
 		},
@@ -48,10 +44,8 @@ func mkCommandFunc(c *cli.Context, ki client.KeysAPI) {
 		handleError(ExitBadArgs, errors.New("value required"))
 	}
 
-	ttl := c.Int("ttl")
-
 	ctx, cancel := contextWithTotalTimeout(c)
-	resp, err := ki.Set(ctx, key, value, &client.SetOptions{TTL: time.Duration(ttl) * time.Second, PrevExist: client.PrevIgnore})
+	resp, err := ki.Create(ctx, key, value)
 	cancel()
 	if err != nil {
 		handleError(ExitServerError, err)