TST: test_reshape.py issues
`test_custom_var_and_value_name` refers to several variables which aren't defined, namely `df`, `var_name`, and `value_name`, all of which should probably have `self.` in front of them:

```
        result18 = melt(df, id_vars=['id1', 'id2'],
                        value_vars='A', var_name=self.var_name, value_name=self.value_name)
        self.assertEqual(result18.columns.tolist(), ['id1', 'id2', 'var', 'val'])

        result19 = melt(self.df, id_vars=['id1', 'id2'],
                        value_vars=['A', 'B'], var_name=self.var_name, value_name=self.value_name)
        expected19 = DataFrame({'id1': self.df['id1'].tolist() * 2,
                                'id2': self.df['id2'].tolist() * 2,
                                var_name: ['A']*10 + ['B']*10,
                                value_name: self.df['A'].tolist() + self.df['B'].tolist()},
```

But I was a little surprised that this wasn't causing an exception, and it turns out to be because `test_reshape.py` contains

```
   def test_custom_var_and_value_name(self):
        [code here]

   def test_custom_var_and_value_name(self):
        self.df.columns.name = 'foo'
        result20 = melt(self.df)
        self.assertEqual(result20.columns.tolist(), ['foo', 'value'])
```

and so the original test is getting clobbered.  I'm not sure if they should be merged or if since the second one changes `self.df` it needs to be kept on its own or not.
