parse military time zone letters

```py
>>> s = format(t, "%T@America/New_York")
>>> parse_time("%T", s)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ora.ParseError: parse error at pattern pos 1, string pos 19
>>> s
'2018-07-12T13:31:03Q'
```
