Setup ignores for flake8
Fix the style of the code base to better match pep8
Run flake8 as part of the test suite
Merge pull request #1509 from dstufft/flake8

Use Flake8 to enforce code style
Use Flake8 on the test of pip's Python files
Ignore the test data's flake8 results
Run flake8 on the entire repository
Merge pull request #1515 from dstufft/more-flake8

More flake8
Use Travis to handle the Matrix
Merge pull request #1498 from dstufft/dynamic-toxenv

[WIP] Use Travis to handle the Matrix
Merge pull request #1514 from dongweiming/develop

Modify add pip_zip to sys.path method
'pip wheel' should download wheels, when it finds them
when file urls have hash fragments, check it
Merge pull request #1524 from qwcode/download_wheels

'pip wheel' should download wheels, when it finds them
fixes for downloading wheels (Issue #1112)
Merge pull request #1527 from qwcode/wheel_deps

fixes for downloading wheels (Issue #1112)
update changelog
Introduce 'retry' option

Add a 'retry' option which allows to configure how many
retries pip should make before giving up on HTTP request.

When the retries count is specified by user, its value is
passed to HTTPAdapter from requests which handles all
the underlying operations.
update changelog
remove `pip wheel` warnings due to merge of #1524