inspect: format the output of docker inspect

Prior to this patch, one would get the output of docker inspect xxx
as below:

user@server:/mnt$ docker inspect ubuntu
[{
    "Architecture": "amd64",

    ...

    "VirtualSize": 199257566
}
]user@server:/mnt$

The last ']' was on the same line with the prompt, i wonder if it is
really what we want it be, it is a little weird, so i add a '\n' to it.

Signed-off-by: Hu Keping <hukeping@huawei.com>

api/client/commands.go

@@ -882,7 +882,7 @@ func (cli *DockerCli) CmdInspect(args ...string) error {
 		// Remove trailing ','
 		indented.Truncate(indented.Len() - 1)
 	}
-	indented.WriteByte(']')
+	indented.WriteString("]\n")
 
 	if tmpl == nil {
 		if _, err := io.Copy(cli.out, indented); err != nil {