Add unparse_url to urllib3.util.url

This round-trips with parse_url (or at least equivalently by the RFC).
Add url attribute to Url, which gives the same thing as unparse_url()
Improve code coverage
Remove unparse_url, in favor of Url.url
Make something a little clearer
pyOpenSSL: Fix WantWrite issue #412
Doc Fix: Disable compression not encryption
Merge pull request #463 from dstufft/encryption-isnt-disabled

Doc Fix: Disable compression not encryption.
Merge branch 'master' into url_unparse

Conflicts:
	test/test_util.py
Make str(Url) == Url.url
Add myself to CONTRIBUTORS
Cutting new release, v1.9.1
Merge pull request #394 from asmeurer/url_unparse

Add unparse_url to urllib3.util.url
Merge pull request #413 from vitek/issue412_want_write

pyOpenSSL: Fixed #412, WantWrite issue
CHANGES for #394
Merge branch 'master' of github.com:shazow/urllib3
CHANGES for #412
Add failing test with bad message

add a cause to different error types

wip

update cause logic

only use cause for non-error related retries

fix python3 warning

revert test