BUG: Problem with count aggregation of a boolean column
The issue I am having is that in pandas 0.10.0, a count of boolean column with a single item in it would be 1, while a count of multiple items would of course be the number of items. In 0.11.0, it is now True if it is a single item, and the count otherwise. 

Result in 0.10.00

``` console
Single item Groupby
DataFrame
   0   bool
0  0  False
Group By
   0  bool
0  0     1
Multi item Groupby
DataFrame
   0   bool
0  0  False
1  0   True
Group By
   0  bool
0  0     2
```

In 0.11.0, this is now the result:

``` console
Single item Groupby
DataFrame
   0   bool
0  0  False
Group By
   0  bool
0  0  True
Multi item Groupby
DataFrame
   0   bool
0  0  False
1  0   True
Group By
   0  bool
0  0     2
```

Test Code:

``` python
print('Single item Groupby')
dsd = DataFrame.from_records([(0, False)], columns=['0', 'bool'])
print('DataFrame')
print(dsd)
print('Group By')
print(dsd.groupby(['0'], as_index=False).agg({'bool':Series.count}))
print('Multi item Groupby')
dsd = DataFrame.from_records([(0, False), (0, True)], columns=['0', 'bool'])
print('DataFrame')
print(dsd)
print('Group By')
print(dsd.groupby(['0'], as_index=False).agg({'bool':Series.count}))
``'
```
