Fix release commit.
Dont fail if there's no file to be removed.
Added certifi as needed to build docs.

Certifi is now mandatory to test the documentation
without errors.
Disable auto test of code blocks in documentation.

Now the code blocks in the documentation aren't tested
automatically, the 'docset' directive is instead needed.
This way portions of code can be isolated and errors identified
faster.
Fixed documentation tests.

All the code blocks were fixed and tested, changing
URLs where needed for some sites.
The logic behind some tests was slightly modified
to be sure they are more robust.
Merge pull request #428 from kevinburke/make-cleanup

Makefile: Don't fail if there's no file to be removed.
Updated docs (index.rst)

Changed test sites to the chosen ones (see PR #429)
Updated docs (managers.rst)

Changed test sites to the chosen ones (see PR #429)
Merge pull request #429 from joined/master

Make docs examples into real doctests (Fixed #416)
Merge branch 'master' of github.com:shazow/urllib3
Security notes.
Sponsorship shpiel.
Bounty source.
Set socket options before binding. (#427 again)
Fixed flaky tests. (Closes #408 for now.)
Add a missing contributor
Merge pull request #433 from sigmavirus24/add-self-to-contributors

Add a missing contributor.
is_fp_closed checks .closed first
added tests for is_fp_closed
make attr check consistent, fix punctuation