Added __repr__ to Moran I

While the memory address returned is highly informative....I thought that it would be nicer to see a better representation of the class.  Perhaps this is a template for other classes?

Here is an example, generated on a network using GeoDaNet Crimes data and counts per edge.

```python
#Moran's I
res = ps.esda.moran.Moran(y, ntw.w, permutations=99)
print res


        Moran's I: 0.00519268749608

        Normality Assumption
        --------------------
        Expected Value: -0.00331125827815
        Variance of I: 0.001848680825
        Standard Dev. of I: 0.0429962885026
        Z-Value: 0.197783252239
        P-Value: 0.843214650106

        Randomization Assumption
        ------------------------
        Variance of I: 0.00184235970473
        Standard Dev. of I: 0.0429227178162
        Z-Value: 0.198122258023
        P-Value: 0.842949410612

        Permutation Results
        -------------------
        Number of Permutations: 99
        Average Expected Value: -0.00471588766906
        Variance of I: 0.000802558883639
        Standard Dev. of I: 0.0283294702322
        Standardized I: 0.349762105818
        P-Value: 0.363258620035
        

```