Add note about updating system path

Remind users to update system path since script does not. 

Well, at least on Windows it doesn't update PATH. Perhaps this should be qualified?
Merge pull request #1888 from patricktokeeffe/patch-1

Add note about updating system path
get-pip.py option examples

Conflicts:
	docs/installing.rst
break out the examples so we can add a qualifying footnote for --user installs

Conflicts:
	docs/installing.rst
Merge pull request #1944 from qwcode/critical_get-pip_docs

docs for get-pip.py options
Replaces spaces in username.
Merge pull request #1986 from matham/master

Replaces spaces in username.
Revert "Merge pull request #1986 from matham/master"

This reverts commit cb26c0b8cb00d18c75503ce4ee59a95a619e8189, reversing
changes made to bb8c7428ab40dde4af92e696ff518e82e214cd24.
Update the AUTHORS.txt file
Bump verison and changelog for release
Merge branch 'develop'

Conflicts:
	docs/installing.rst
	docs/reference/pip_install.rst
Merge branch 'master' into develop
bump versions for development
Bump development version to 6.0.1.dev0
Ensure that we preserve executable file permission bits
Fix import so exception module is accesible. With the previous import `pip` module wouldn't have any `exceptions` attribute as it's __init__ doesn't actually import it. Fixes the confusing error message from #2067.
fix typo
Restore the list of versions on an error
Warn about `>` being an exclusive operator now.

E.g.: `pip install 'prettytable>0.7'` will no longer install
`prettytable==0.7.2`, because of PEP 440.

Hopefully prevents the kind of confusion see in
https://bitbucket.org/pypa/setuptools/issue/301/101-in-requirementparse-foo-10-results

    $ pip install 'prettytable>0.7'
    Collecting prettytable>0.7
      The behavior of the `>` version specifier has changed in PEP 440. `>` is now an exclusive operator, meaning that >0.7 does not match >0.7.*.
      Perhaps you want `>=` instead of `>`?
      Could not find a version that satisfies the requirement prettytable>0.7 (from versions: )
      No distributions matching the version for prettytable>0.7
Revert "Speed up unpack_file_url"