Support resample('D').agg(new_col_name=('col_name',  func) )
Normal agg support:

```
df.agg(
    sale_hour=('sale_count', 'count')
)
```

![image](https://user-images.githubusercontent.com/3938751/92679253-7a23e380-f35a-11ea-978e-46bacebcfb1f.png)

But resample().agg doesn't :

```
df.resample('D').agg(
    sale_hour=('sale_count', 'count')
)
```
got 
```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-159-8afb38e3b96b> in <module>
      1 df.resample('D').agg(
----> 2     sale_hour=('sale_count', 'count')
      3 )

TypeError: aggregate() missing 1 required positional argument: 'func'
```


-----

Now I have to write 
```
df.resample('D').agg(
dict(
    sale_count="sum",
    home_rec="mean",
    discount_money_rate="mean",
    is_flashsale="mean",
    is_plan_market="mean",
    is_plan_store="mean",
    discount_rate="mean",
    in_stock_rate="mean",
),
).join(
    df.resample('D').agg(
    dict(
        sale_count="count",
    ),
    ).rename(columns={'sale_count':'sale_hours'})
)
```

This because rename multiple level is much more difficult  than join .


