Drop support for python 2.6.

Update c-ares to 1.11.0

- Replaced the whole directory with current source. This adds a few more
  scripts that we could remove again if desired, but it's easier just to
  be able to copy everything.
- However, the new test directory requires c++11, which travis doesn't
  have, so it's ditabled.
- The invocation of configure had to lose the CONFIG_FILES= param,
  because with that set, configure would fail to create the Makefile
  which in turn caused the whole thing to fail.

Test non-embedded versions of libev and c-ares

Downstream distributors like to use their system libraries for some
reason, so make sure that works, at least with the versions we have.
Previously at least one test was broken.

Fixes #759

On travis, start a build with 2.7.8 so that _ssl2.py gets
tested (previously tested by Python 2.6). Do so with the test_ssl.py
from that version (because the changes are large), but keep using the
2.7.11 tests with just a few removals otherwise.

Update tblib to 1.3.0

Update libev to 4.22

Grab the latest ev.c from CVS, r1.480, which moves around the modifiers to fix the noinline problem.

Grab the latest ev.c from CVS, r1.480, which moves around the modifiers to fix the noinline problem.

Issue some warnings for patch_all with invalid parameters

Update socket docs to clarify their duplication of stdlib interface; tone down the warnings. [skip ci]

See changelog.rst for details.

Also skip the 'make' step on Windows if installing from an sdist (piggyback the Unix method of looking for Makefile/Makefile.ext). Ref #757.

Notes about cython on windows. XXX: Duplicated a couple places, intro.rst and README.rst, we should refactor.

- Kill older builds for the same PR automatically.
- Separate building and running tests.
  This lets us build and install a wheel up front so we don't have to do
  it again after running the tests (to distribute). This shaves 1+
  minute off each build for faster overall feedback.

Ignore the BlockingIOError name in server.py if running pyflakes on Py2; also sort the error lines by filename so they're easier to find. [skip ci]