Rework how SSL protocol_version is handled

* Don't ignore SSL protocol_version in embedded mode

* Stop setting global default SSL protocol_version

* Warning that R16B01 is required to SSL protocol_version
    After testing R14B02+ with `application:set_env(ssl, protocol_version, X)`
    and passing `versions` to `ssl:listen`, it looks like only R16B01+ follows
    the settings.

    References:
      - https://travis-ci.org/capflam/otp-ssl-test/builds/44369449
      - http://erlang.org/pipermail/erlang-questions/2014-October/081388.html
      - https://github.com/klacke/yaws/pull/192

Fix pull request #193
Add Andrei Neculau in the contributors (and sort them by name)
Add Erlang/OTP 17.3 support in .travis.yml
Merge remote-tracking branch 'upstream/master'