Fix single day problem

I added two tests.
```javascript
assertEqual('2012.1.9', $.format.date('Wed Jan 09 06:23:38 PST 2012', 'yyyy.M.d'));
assertEqual('1.9.2012', $.format.date('Wed Jan 09 06:23:38 PST 2012', 'M.d.yyyy'));
```

results
```
Failure: assertEqual
expected <'2012.1.9'>, actual: <'2012.M.'> Line #216
Failure: assertEqual
expected <'1.9.2012'>, actual: <'1.d.2012'> Line #217
```

so I make it works. :)