Some cleanups in stats

Playing with PyCharm, may as well get it to do something semi-useful....

This is mainly:

- PEP8 fixes
- changes in docstrings (imports) to conform to numpy doc standard
- removing extraneous parenthesis
- changing to in-place operations where possible

Ralf, sorry to nitpick, but with scipy 0.14.0 and with this PR, I get

```
In [6]: stats.kstat(data, 1)
Out[6]: 0.011315963643974305

In [7]: stats.kstat(data, 2)
Out[7]: 1.0179311469776793

In [8]: stats.kstat(data, 3)
Out[8]: 0.058110522631750268

In [9]: stats.kstat(data, 4)
Out[9]: 0.075413401016988763
```
so the values in `expected` should really be

    expected = [0.011316, 1.017931, 0.05811052, 0.0754134]

(Did you actually get 0.0754137 with n=4?)