parse_editable: clarify output

extras and editable_options are two different things
Fix environment extras installation for sdist

use pkg_resources.Distribution.requires instead of
Requirements.requirements to have environment markers parsing for free
It also unifies a little the process for wheel and non-wheel installs

closes #2174
drop egg_info_lines

and use pkg_resources.Distribution instead
switch extra requirements log to debug
Fix ``pip list`` when there is an invalid PEP 440 version installed
Merge pull request #2153 from xavfernandez/xfernandez/extras_fix

Fix extras_require and environment markers in sdist
Update changelog
Merge pull request #2236 from dstufft/fix-pip-list-invalid-version

Fix ``pip list`` when there is an invalid PEP 440 version installed
Split up Secure vs Insecure for the requests HTTPAdapters
Use the --trusted-host argument to disable TLS verification as well
Revert "Add option --no-check-certificate to skip ssl cert verification"

This reverts commit 9a9d7acefe2168c84ab135501284b78827ab58b2.

Conflicts:
	pip/cmdoptions.py
Adjust changelog to switch from --no-check-certificate to --trusted-host
Adjust the --trusted-host help option
Adjust tests to compensate for --trusted-hosts
Merge pull request #2237 from dstufft/consolidate-security

Treat HTTP and invalid HTTPS the same
Document an alternative to pip bundle
Merge pull request #2238 from dstufft/document-bundle-alternative

Document an alternative to pip bundle
simplify unpack_url

and move write_delete_marker_file logic to req_set