pandas.read_ functions crashes on read from url with space characters
```python
import pandas
pandas.read_json('http://httpbin.org/anything/something something')
```
python throws exception
`HTTPError: HTTP Error 505: HTTP Version Not Supported`

if url escaped:
```
pandas.read_json('http://httpbin.org/anything/something%20something')
```
then it works as expected

#### Problem description

#### Expected Output

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

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-96-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: ru_RU.UTF-8
LANG: ru_RU.UTF-8
LOCALE: None.None

pandas: 0.20.3
pytest: None
pip: 9.0.1
setuptools: 36.5.0
Cython: None
numpy: 1.13.3
scipy: None
xarray: None
IPython: 5.5.0
sphinx: None
patsy: None
dateutil: 2.6.1
pytz: 2017.2
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 2.1.0
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: 1.0b10
sqlalchemy: None
pymysql: None
psycopg2: 2.7.3.1 (dt dec pq3 ext lo64)
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: None

</details>
