BUG: pd.Timedelta np.int, np.float. fixes #8757

closes #8757 
hmm, you are not supposed to modify a dict in the same look, instead do something like this:

```
def convert(value):
    if isinstance(value, (int, float)):
       pass
    elif np.issubdtype(value, int):
       value = int(value)
    elif np.issubdtype(value, float):
       value = float(value)
    return value
kwargs = dict([ (k, convert(v)) for k, v in compat.iteritems(kwargs) ])
```