Bug with sql.write_frame - not possible to write Dataframe to SQLite DB
Additionally to the broken replace option ( https://github.com/pydata/pandas/issues/4110 ) the sql.write_frame function does not work anymore for me with 0.13 when trying to write a Dataframe into a SQLite DB:

```
sql.write_frame(frame, name=name, con=conn, if_exists='replace')
```

results in :

``` python
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/sql.py", line 228, in write_frame
    func(frame, name, safe_names, cur)
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/sql.py", line 244, in _write_sqlite
    cur.executemany(insert_query, data)
sqlite3.InterfaceError: Error binding parameter 0 - probably unsupported type.
```

The same code did work before without issues.

EDIT: I solved the problem by adding:

``` python
frame['index']=frame['index'].astype(long)
```

The index column was stored as datetime64 dtype before. Still don't know why my code broke, before it worked without type conversion.
