lineterminator in to_csv doesn't work
```
In [3]: df = pd.DataFrame({'a': ['3.4', '34.400'], 'b': ['5,5', '10,200']})

In [4]: df
Out[4]:
        a       b
0     3.4     5,5
1  34.400  10,200

In [5]: df.to_csv(lineterminator='-')
Out[5]: ',a,b\n0,3.4,"5,5"\n1,34.400,"10,200"\n'
```

I would've expected

```
Out[5]: ',a,b-0,3.4,"5.5"-1,34.400,"10,200"-'
```
