to_datetime parsing odd strings to dates
Some strings that clearly aren't dates are being parsed as dates. This may be expected behavior, but thought I'd flag just in case.

``` python
pd.to_datetime('0067000000M2M3HAAV')
Timestamp('2015-02-05 00:02:03')
```

Not sure how this matches to 2015! But this is fine:

``` python
pd.to_datetime('0067000000M2LkvAAF')
'0067000000M2LkvAAF'
```
