sort seems to sort inplace by default unlike documentation
Hello,

I noticed

```
df_ohlc['high'].sort(ascending=False)
```

raises

```
ValueError: This Series is a view of some other array, to sort in-place you must create a copy
```

which seems to mean that, by default, sort uses by default `inplace=True`

but according to

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.sort.html

```
inplace : boolean, default False
```

Here is a minimal example:

```
import pandas as pd
import numpy as np
N = 1000
rng = pd.date_range('1/1/2011', periods=N, freq='H')
s = pd.Series(np.random.random(N), index=rng)
df_ohlc = s.resample('1D', how='ohlc')
df_ohlc['high'].sort(ascending=False)
```

raises `ValueError: This Series is a view of some other array, to sort in-place you must create a copy`

```
df_ohlc['high'].sort(ascending=False, inplace=True)
```

raises same exception

but

```
df_ohlc['high'].sort(ascending=False, inplace=False)
```

doesn't raises exception

Kind regards
