The truth value of a Index is ambiguous

[Rambatino]

  File "/Users/Mark/clients/kruskals/Kruskals/kruskals.py", line 46, in from_pandas_df
    return Kruskals(ind_values, dep_values, i_vars)
  File "/Users/Mark/clients/kruskals/Kruskals/kruskals.py", line 24, in __init__
    if i_vars and len(i_vars) != ndarr.shape[1]:
  File "/Users/Mark/anaconda/envs/quattro8/lib/python2.7/site-packages/pandas/indexes/base.py", line 1388, in __nonzero__
    .format(self.__class__.__name__))
ValueError: The truth value of a Index is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
^CException SystemExit: 0 in <module 'threading' from '/Users/Mark/anaconda/envs/quattro8/lib/python2.7/threading.pyc'> ignored

This occurs if you pass a numpy array of the column names, rather than a python list

[Rambatino]

Fixing in #9