Time.new with explicit timezone string will display as UTF with +00:00.

```text
jruby -e 'time = Time.new(2013, 2, 20, 0, 0, 0, "+00:00"); p time'
```
We display:

```text
2013-02-20 00:00:00 UTC
```

MRI displays:

```text
2013-02-20 00:00:00 +0000
```

If we supply anything else we match MRI:

```text
jruby -e 'time = Time.new(2013, 2, 20, 0, 0, 0, "+10:00"); p time'
2013-02-20 00:00:00 +1000
```

