Revert "Proxy urls should have explicit schemes."

This reverts commit 840540b6b1f07ef87faab73392c03fbef0dcc9fe.

Conflicts:
	requests/adapters.py
	requests/utils.py
Default proxy scheme to http.
Add documentation about decode_unicode.
Always honor decode_unicode, even when _content is present.

--HG--
extra : amend_source : 25977a1227b163d49bf2e1aec6aa448e5cd3be8a
Add tests for decode_unicode
Add __str__ to case insensitive dict. Logging headers for debugging purposes is often necessary, and the currently logging the headers would be using __repr__ which would log the implementation detail of headers, caseinsensitivedict. Adding str lends a more printing and log friendly implementation for case insentitice dict
Fix parenthesis typo
Shorten str for case insensitive dict
Add urllib3 util package to setup.py.
Remove the easy_install section

There's not a lot of good reason to actually call out easy_install at all.
Anyone who prefers it already knows it exists and everyone else should be
directed unambiguously towards pip.
Merge pull request #2032 from dstufft/patch-1

Remove the easy_install section
Merge pull request #2026 from Lukasa/updateurllib3

ImportError: No module named 'requests.packages.urllib3.util'
Remove references to not-yet-made 2.3.0 release.
Update urllib3 to 4fb351cd2
Merge pull request #2038 from dstufft/update-urllib3

Update urllib3 to 4fb351cd2
Merge pull request #1937 from jaraco/master

Improved decoding support for Response.iter_content and iter_lines
Merge pull request #1924 from schlamar/proxy-default-scheme

Default proxy scheme to HTTP
Merge pull request #1972 from avidas/response_str

Add __str__ to case insensitive dict
CaseInsensitiveDict now looks like a normal dict
Initial 2.3.0 changelog.