Inconsistent results for np.isreal with strings
Hi Pandas.

Just uncovered a clear bug in the interaction between pandas series and numpy isreal().  The behavior is simple: isreal() produces incorrect results on panda's series that include string types.  It's not 100% clear the underlying cause but it appears to be related to np.isreal operating over the pd.Series object because isreal returns the correct result when individual elements are accessed.  See example reproducing the issue in pandas 0.16.1:

```
print(np.isreal(pd.Series(['1.0'])))
print(np.isreal(np.array(pd.Series(['1.0']))))
print(np.isreal(np.array(pd.Series(['1.0']))[0]))
print(np.isreal(np.array(pd.Series(['1.0'])[0])))
print(np.isreal(np.array(['1.0'])))
```

produces

```
[ True]
[ True]
False
False
False
```
