Make `pip show` show much more metadata

New fields:
  - Metadata-Version
  - Summary
  - Home-Page
  - Author
  - Author-email
  - License
  - Entry-points

Sample output:

    $ pip show pytest
    ---
    Metadata-Version: 1.1
    Name: pytest
    Version: 2.6.4
    Summary: pytest: simple powerful testing with Python
    Home-page: http://pytest.org
    Author: Holger Krekel, Benjamin Peterson, Ronny Pfannschmidt, Floris Bruynooghe and others
    Author-email: holger at merlinux.eu
    License: MIT license
    Location: /Users/marca/python/virtualenvs/tmp-4e2169280f5cbd16/lib/python3.4/site-packages
    Requires: py
    Entry points:
      [console_scripts]
      py.test = pytest:main
      py.test-3.4 = pytest:main
Don't retry when attempting to check the pip version
Use a smaller timeout by default on the pip version check
Imply --disable-pip-version-check when --no-index is used
Correctly handle options with pip in their name
Don't check pip version in tests
Merge pull request #2270 from dstufft/speed-up-version-check

Speed up version check
Bump version for development of 6.0.3
Small tweak to changelog
Merge pull request #2270 from dstufft/speed-up-version-check

Speed up version check
(cherry picked from commit 34f5befaae38fe180cd1d6309558da192967f452)
Merge branch 'release/6.0.3'
bump version for release
Generate a new get-pip.py
Merge branch 'master' into develop

Conflicts:
	CHANGES.txt
	pip/__init__.py
Merge pull request #2232 from msabramo/make_show_more_awesome

Make `pip show` show much more metadata
Fix progress bar since Windows doesn't support ANSI escape codes

* Use the colorama module to enable the "clear the line" ANSI escape
  code on Windows.
* Disable cursor hiding on Windows since Windows terminal doesn't
  support it nor does colorama.
Merge pull request #2281 from dstufft/windows-progress-bar

Fix progress bar since Windows doesn't support ANSI escape codes
Detect if a nicer progress bar can be used, and use it if so

Conflicts:
	pip/utils/ui.py
Merge pull request #2231 from dstufft/unicode-bar

Use a nicer progress bar if possible
Fixed minor typo in changelog