Add support for mbed TLS (formerly PolarSSL)

[jirutka]

Could you please consider adding support for some more secure and lightweight TLS implementation, such as mbed TLS (formerly PolarSSL)?

[daurnimator]

Is there a set of mbed/PolarSSL TLS lua bindings we can be compatible with?

[jirutka]

I found these two, but neither of them has any release, so they are probably incomplete:

• mah0x211/lua-mbedtls
• zaherm/lua-mbedtls

[daurnimator]

I would argue that there needs to be a high quality mbedtls lua library to create and manage TLS contexts before cqueues adds compatibility for it.

[luveti]

It looks like a library that can create and manage TLS contexts now exists! https://github.com/neoxic/lua-mbedtls (docs links https://github.com/neoxic/lua-mbedtls/blob/master/doc/ssl.md)

[lePereT]

It would be great if cqueues (and by extension @daurnimator's excellent lua-http supported mbedtls, especially in the context of working with embedded linux where space is at a huge premium. now that complete lua bindings exist what would be the scale of this change?