shouldn't pandas.Index.tolist convert from numpy datatypes to native Python datatypes?
I wonder if it wouldn't be better/less surprising if Index.tolist did that conversion. FWIW, I was bitten by it via xlwings which tries to send an index values to Excel via COM by using index.tolist() and since the COM layer only handles basic Python types, it breaks. The patch seems trivial (I can submit a PR if you like), but I don't know whether you'd accept that, nor if it would have any implications.

``` diff
- return list(self.values)
+ return self.values.tolist()
```

FWIW, it seems to be related to #10904.
#### Code Sample, a copy-pastable example if possible

``` python
import pandas as pd
import numpy as np

df = pd.DataFrame(np.zeros((3, 4)), index=np.arange(3))
l = df.index.tolist()
print(type(l[0]))
# <class 'numpy.int64'>
```
#### Expected Output

`<class 'int'>`
#### output of `pd.show_versions()`

python: 3.5.1
pandas: 0.18.0
numpy: 1.10.4
