Show coverage information for tests

Run the unit tests before the integration tests

Use a regex to avoid hard coding version branches

Clarify requirement specifier format

req: Support --no-use-wheel flag in requirements.txt

Query installed requirements for extras

fixes issue where egg_info('requires.txt') does not exist
for packages installed from wheels.

Removed reduce from pip's compat module

It already has a consistent location across Py2/3.

Remove unnecessary imports, move some to six

Overwrite old scripts when installing from wheel.

Fix #1101 - Properly handle a <base> without a href

Fix #1319 - Allow use of Zip64 extension

Fix #1680 - Use System SSL Certificates if Available

Support earlier OS X versions in wheels

Catches BadCommand in get_src_requirement()

Don't rely on appspot

Default from pip 1.6 will be to always use wheels, so the --use-wheels
in requirements.txt is now deprecated. However, the --no-use-wheels
is introduced to be able to disable wheel usage via requirements.txt.

Github's online editor is bad...

Fixes #1800

If you use single or double quotes in a `requirements.txt` file, pip exits with an error. This change clarifies that single or double quotes should only be used in the shell.