to_csv puts extra comma before columns
Version: '0.13.1-648-gad1f47d'

``` python
towrite.to_csv()
',jdate,orbit,sundist\n2010-12-20 10:00:00.074000,2455550.916667521,6867.0,0.98631\n2010-12-20 10:00:00.202000,2455550.916669002,6867.0,0.98631\n2010-12-20 10:00:00.330000,2455550.916670484,6867.0,0.98631\n2010-12-20 10:00:00.458000,2455550.916671965,6867.0,0.98631\n2010-12-20 10:00:00.586000,2455550.916673446,6867.0,0.98631\n'
```
