Into clientdataset

Just a couple of routes.  Note that most other things can be done by composing these, e.g. 

    into(np.ndarray, into(DataFrame, 'blaze://localhost::accounts'))

I plan to automate something like the composition above in moderate future so I'm hesitant to do it piecemeal here.

Does this handle current requirements @hhuuggoo ?  I can also put in any particular solution.  Just not planning on handling them all.