Add shuffling behavior / utility method

[cancan101]

Ideally some utility method that works to shuffle both dataframes, series and numpy arrays.

For example to shuffle a Dataframe: df.ix[shuffle(df.index)].

See scikit-learn/scikit-learn#4008 for discussion.

[jreback]

see #7274 (and the original issue #2419 )

closing as a dupe