Timedelta returns wrong value
#### Code Sample

```python
In [6]: pd.Timedelta(6, 'M')
Out[6]: Timedelta('182 days 14:54:36')

In [7]: pd.Timedelta('6M')
Out[7]: Timedelta('0 days 00:06:00')

In [8]: pd.Timedelta(6, 'W')
Out[8]: Timedelta('42 days 00:00:00')

In [9]: pd.Timedelta('6W')
Out[9]: Timedelta('42 days 00:00:00')

```
#### Problem description

Out[7] shoud return 182 days but 6 minutes