Is it possible to remove (not to show) column names in pandoc tables?  

If I use `pander` (or `pandoc.table`) function it prints column names automatically. 

```
> pander(iris[1:4, ])

-------------------------------------------------------------------
 Sepal.Length   Sepal.Width   Petal.Length   Petal.Width   Species 
-------------- ------------- -------------- ------------- ---------
 5.1            3.5           1.4            0.2       setosa  

 4.9             3            1.4            0.2       setosa  

 4.7            3.2           1.3            0.2       setosa  

 4.6            3.1           1.5            0.2       setosa  
-------------------------------------------------------------------

```

Expected output should be:

```
-------------------------------------------------------------------
 &nbsp;         &nbsp;        &nbsp;        &nbsp;         &nbsp; 
-------------- ------------- -------------- ------------- ---------
 5.1            3.5           1.4            0.2       setosa  

 4.9             3            1.4            0.2       setosa  

 4.7            3.2           1.3            0.2       setosa  

 4.6            3.1           1.5            0.2       setosa  
-------------------------------------------------------------------

```