read_csv: delim_whitespace ignored when skip_footer is set
The `delim_whitespace` options no longer works when specifying a `skip_footer` other then zero. I can replicate the behavior in 0.12 with the following example:

```
import pandas as pd
from StringIO import StringIO

indata = StringIO("""1.2   5.6   8.5
4.5   6.7   6.4


""")

indata.seek(0)
df = pd.read_csv(indata, delim_whitespace=True, header=None, skip_footer=2)
```

Which returns:

```
                 0
0  1.2   5.6   8.5
1  4.5   6.7   6.4
```

Note how its only one column, instead of three. Changing the `skip_footer` to 0 makes it work as expected. 

```
indata.seek(0)
df = pd.read_csv(indata, delim_whitespace=True, header=None, skip_footer=0)
```

Returns:

```
     0    1    2
0  1.2  5.6  8.5
1  4.5  6.7  6.4
2  NaN  NaN  NaN
3  NaN  NaN  NaN
```

If the above example is used with something like `names=['a','b','c']` an (obvious) 'ValueError' exception occurs: `Expected 3 fields in line 1, saw 1`. 
