Tests for unicode_content inside response

Tested unicode_content value whether charset is set or not.

Signed-off-by: Alexandre Barbosa <alexandreab@live.com>
Signed-off-by: Carlos Oliveira <carlospecter@gmail.com>
Helper function to mock responses
PEP8 fixes
Fixed doc reference
Improving HttpProxyResponse tests

Signed-off-by: Alexandre Barbosa <alexandreab@live.com>
Signed-off-by: Carlos Oliveira <carlospecter@gmail.com>
Tests for charset in Content-Type

Added response factory as a parameter to patcher so that it returns
proxy response instead of a magic mock
Tested secure and unsecure host replacement
Refactored tests and factory to work with Python 3

Had to refactor tests to work on both Python 3 and Django 1.6 besides
Python 2 and Django 1.7
Tests for response header, status code and content

Testing whether the response headers returned are not in the Hop by Hop
headers dict, if the status code return is the same as the sent one and
whether the content remained the same
Improved tox config
Removed version specific code from coverage
Added flake8 check before tests
Added flake8 as deps
Added diazo as test dependency
Reusing CustomView code
Fixed flake8 checks
Added some tests for transformer
Replaced assertEquals by assertEqual
Updated docs

[skip ci]
Rewrite implementation