feat: add support for SSL/TLS

[rtm-ctrlz]

Added usage of stream_context_set_option for setting SSL/TLS options. Added tests with certificate generation and SSL/TLS-enabled configuration for RabbitMQ. Added some configuration examples for common use cases see examples/tls directory. Mentioned SSL/TLS support in main README.md.

Some notes:

• RabbitMQ added sysctl format since 3.7.0, so there are both configuration file versions prior 3.7.0 and sysctl.
• Tests covers only connections, any other tests should works same way as via plain tcp.
• There is no way to detect any errors in SSL/TLS options, so in case of error we will get exception with Could not connect to... message.

Resolves #77

[WyriHaximus]

For future reference: Went with #88 instead of this PR, because it looks neater