Squashed commit of the following:

commit a130bf42788b7fa45186acb12dae8721697c84ee
Author: Joerg Rings <jrings@civisanalytics.com>
Date:   Fri Oct 24 14:36:39 2014 -0500

    Drop printing v altogether

commit f7436b2c87064f43cfc65f5085cd53dafec5fd65
Author: Joerg Rings <jrings@civisanalytics.com>
Date:   Fri Oct 24 13:53:37 2014 -0500

    Fixed an error in _split_data

    ValueError message would fail itself when v wasn't already a np.array,
    e.g. for a list of strings
Merge branch 'develop' of github.com:jrings/pystan into develop