DataFrame.drop() does not recognise the columns keyword argument
#### Code Sample, a copy-pastable example if possible

```python
index = np.linspace(-3, 5, 7)
df = pd.DataFrame({'A': np.sin(index), 'B': np.cos(index**2)}, index=index)
df.drop(columns=['A'])

```
#### Problem description

The [docs ](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.drop.html) say that I can use the `columns` keyword, but when I try I get the following error:

```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-139-3a18b0426444> in <module>()
      2 df = pd.DataFrame({'A': np.sin(index), 'B': np.cos(index**2)}, index=index)
      3 # type(df.apply(np.sum, axis=1, reduce=False))
----> 4 df.drop(columns=['A'])

TypeError: drop() got an unexpected keyword argument 'columns'

```

The following is a workaround:

```
df.drop('A', axis=1)
```

#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.2.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 94 Stepping 3, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.20.3
pytest: 3.2.1
pip: 9.0.1
setuptools: 36.5.0.post20170921
Cython: 0.26.1
numpy: 1.13.1
scipy: 0.19.1
xarray: None
IPython: 6.1.0
sphinx: 1.6.3
patsy: 0.4.1
dateutil: 2.6.1
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.4.2
numexpr: 2.6.2
feather: None
matplotlib: 2.0.2
openpyxl: 2.4.8
xlrd: 1.1.0
xlwt: 1.3.0
xlsxwriter: 0.9.8
lxml: 3.8.0
bs4: 4.6.0
html5lib: 0.999999999
sqlalchemy: 1.1.13
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: None

</details>
