WARN: numpy warnings on operations
```
pandas/tests/frame/test_operators.py::TestDataFrameOperators::()::test_comparison_invalid
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise == comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise == comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise != comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise != comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise == comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise == comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise != comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:104: DeprecationWarning: elementwise != comparison failed; this will raise an error in the future.
    result = op(self.values, np.asarray(other))
```

cc @jbrockmendel I think some recent changes exposed these (or they are new in numpy 1.14.1tons).

should not just catch these, rather handle intelligently. IIRC these are for a comparison of ``None``

lots of warnings that need catchng / fixing: https://travis-ci.org/pandas-dev/pandas/jobs/349648610

