BUG: Interpolation with 'limit' argument gives error when there are no nan values in the data series
See the following code:

``` python
from pandas import DataFrame
from numpy import NaN
df = DataFrame({'A': [1,2,3,5]})

# interpolation with 'limit' argument gives error when there are
# no nan values in the series:
df.interpolate(limit=1)

# after adding a NaN value, no error
df.loc[1] = NaN
df.interpolate(limit=1)
```

the bug appears to be in pandas/core/common.py. The datatype for 

``` python
1438   violate = np.array([x.all() & (x.size > limit) for x in violate],) 
```

is implicit, and should be made explicit with dtype=bool.
