Inconsistent plotting of DateTimeIndex
#### Code Sample, a copy-pastable example if possible

```python
%matplotlib inline
import seaborn
import pandas as pd
import numpy as np
dates = pd.date_range('2016-01-01', '2016-12-31', freq='D')
s = pd.Series(np.random.uniform(size=366), index=dates)
```
```
s.plot(kind='line')
```
![line](https://user-images.githubusercontent.com/50109/28294672-8c06921c-6b29-11e7-8f41-fe1fce8039cb.png)

```
s.plot(kind='bar')
```
![bar](https://user-images.githubusercontent.com/50109/28294664-7643af32-6b29-11e7-8cc9-50a2767d9cc5.png)


#### Problem description

```line``` and ```bar``` displays dates differently as per screenshots attached.

#### Expected Output

Both ```line``` and ```bar``` displaying dates the same (preferably the readable layout)

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

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 4.10.0-26-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: None.None

pandas: 0.20.3
pytest: 3.1.2
pip: 9.0.1
setuptools: 36.0.1
Cython: None
numpy: 1.13.1
scipy: 0.19.0
xarray: None
IPython: 5.4.1
sphinx: None
patsy: 0.4.1
dateutil: 2.6.1
pytz: 2017.2
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 2.0.2
openpyxl: None
xlrd: 1.0.0
xlwt: None
xlsxwriter: None
lxml: None
bs4: 4.6.0
html5lib: 0.999999999
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: 0.5.0
</details>
