fix table output for multibyte characters

Displaying multibyte characters fail for table outputs.

how to reproduce

```
# create a multibyte tags
$ aws ec2 create-tags  --resources ami-xxxxxxxx --tags  Key=Name,Value=✓
{
    "return": "true"
}
# list tag info w/ table output
$ aws ec2 describe-instances --output table
'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)
```