title: Deprecation warning in scikit-learn svmlight format loader
body: <p>I'm getting a new deprecation warning in an IPython notebook I wrote that I've not seen before. What I'm seeing is the following:</p>
  
  <pre><code>X,y = load_svmlight_file('./GasSensorArray/batch2.dat')
  /Users/cpd/.virtualenvs/py27-ipython+pandas/lib/python2.7/site-packages/sklearn/datasets/svmlight_format.py:137: DeprecationWarning: using a non-integer number instead of an integer will result in an error in the future
  return _load_svmlight_file(f, dtype, multilabel, zero_based, query_id)
  /Users/cpd/.virtualenvs/py27-ipython+pandas/lib/python2.7/site-packages/sklearn/datasets/svmlight_format.py:137: DeprecationWarning: using a non-integer number instead of an integer will result in an error in the future
  return _load_svmlight_file(f, dtype, multilabel, zero_based, query_id)
  ...
  </code></pre>
  
  <p>Any thoughts on what might be the issue here? I took another look at my data file and at first glance, I don't see any obvious issue. I'm not sure what I changed in my system setup that would have caused this. I've got v. 0.14.1 of scikit-learn installed. </p>