[3.4] Backport CI config from master by vstinner · Pull Request #2475 · python/cpython

* Add .travis.yml for Travis CI
* Add .github/ for AppVeyor and CodeCov.

The regen-all Makefile rule doesn't exist in Python 3.4, only since
Python 3.5 and newer (and 2.7).

tzdata resource doesn't exist in Python 3.4.

Fixing Sphinx warnings requires to backport huge intrusive changes
like:

- commit d97b7dc
- commit 5c67933

The public cyrus.andrew.cmu.edu IMAP server (port 993) doesn't accept
TLS connection using our self-signed x509 certificate. Remove the two
tests which are already skipped.
(cherry picked from commit 7895a05)

On Windows a symlink can has the FILE_ATTRIBUTE_DIRECTORY flag.

(cherry picked from commit 388b90f)

Fix test_invalid_cmd() and test_invalid_env(), TypeError is raised on
Python 3.4.

(cherry picked from commit 5e22721)