Incorrect toString format for hours

```
What steps will reproduce the problem?
1. create a date where the HOUR is 0 (12am)
2. format the date to string using toString('h')

What is the expected output? What do you see instead?
I expect to see "12", to represent 12 am - conforming to
http://code.google.com/p/datejs/wiki/FormatSpecifiers

h The hour of the day between 1-12. "1" to "12"

Instead I see "0"

What version of the product are you using? On what operating system?
Latest version. Chrome (latest) on Windows 7

Please provide any additional information below.

```

Original issue reported on code.google.com by `nimblea...@gmail.com` on 31 May 2012 at 12:14