read_csv character encoding bug?
This is a weird one from [StackOverflow](http://stackoverflow.com/questions/14488697/pandas-read-csv-failing-on-columns-with-null-characters), this file has some `\x00`s which seem to be ignored when printing but confuse `read_csv`:

```
x = 'x,y\n \x00\x00\x00,Reg\n \x00\x00\x00,Reg\nI,Swp\nI,Swp\n'
X = StringIO(x)

In [3]: pd.read_csv(X)
Out[3]: 
     x    y
0          
1  NaN  NaN
2    I  Swp
3    I  Swp

In [4]: print x
x,y
 ,Reg
 ,Reg
I,Swp
I,Swp
```
