Standard scaler sparse matrix with_std default changed to auto

Solves   Issue #1724

Although I am having following fail in test. How should I deal with it?
```
======================================================================
FAIL: sklearn.tests.test_common.test_estimators_overwrite_params
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/nose/case.py", line 187, in runTest
    self.test(*self.arg)
  File "/home/hrishi/scikit-learn/sparse3/sklearn/tests/test_common.py", line 951, in test_estimators_overwrite_params
    % (name, k, v, new_params[k]))
AssertionError: Estimator StandardScaler changes its parameter with_std from auto to True during fit.
    'Estimator StandardScaler changes its parameter with_std from auto to True during fit.' = self._formatMessage('Estimator StandardScaler changes its parameter with_std from auto to True during fit.', "%s is not false" % safe_repr(True))
>>  raise self.failureException('Estimator StandardScaler changes its parameter with_std from auto to True during fit.')
    

----------------------------------------------------------------------
Ran 1831 tests in 185.116s

FAILED (SKIP=14, failures=1)

```