2 spaces in csv file between date and time
```
df.to_csv(path_or_buf=f, sep=' ', header=False, 
                index=True, mode='a', quoting=QUOTE_NONE, escapechar=' ',
                date_format='%m/%d/%Y %H:%M:%S')
```

generates 2 spaces in csv file between date and time. It should only be one space since sep=' '.
