Cannot use np.round or np.around on Float64Index
np.round()/np.around() currently don't work on Flaot64Index, because the Float64Index is throwing an error when Float64Index.round() is called.

In our application, we are getting floating point digit discrepancies when doing subtraction and other floating point operations on these indicies, and I believe rounding would solve the problem.

Original mailing list thread:

https://groups.google.com/forum/#!topic/pydata/8aTLVKrPJfs

I'm using pandas.read_csv(), so I can't access the data apriori to it being written into a dataframe to round it before instantiation.
