Drop gives TypeError message for too few arguments when that many are given
This gives an incorrect error message: "takes **at least 2** arguments ( **2** given)".

_Note: I may be using drop wrong here, but the error message is confusing._

```
import pandas as pd
from StringIO import StringIO

csv = StringIO("""ID,NAME,DATE,VAR1
1,a,03-JAN-2013,69
1,a,04-JAN-2013,77
1,a,05-JAN-2013,75
2,b,03-JAN-2013,69
2,b,04-JAN-2013,75
2,b,05-JAN-2013,72""")

df = pd.read_csv(csv, index_col=['DATE', 'ID'], parse_dates=['DATE'])
df.columns.name = 'Params'

In [11]: a = df.unstack('ID').resample('W-THU').unstack()

In [12]: a.drop(level=0)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-93-6ee7c2529aa0> in <module>()
----> 1 a.drop(level=0)

TypeError: drop() takes at least 2 arguments (2 given)

In [13]: a.drop(axis=0, level=0)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-98-081a6501fa61> in <module>()
----> 1 a.drop(axis=0, level=0)

TypeError: drop() takes at least 2 arguments (3 given)
```

_Found when messing about with this [SO question](http://stackoverflow.com/questions/15617496/resampling-a-multi-index-dataframe), which I think may also be a bug..._
