Mainly, this adds support for the meta endpoints /health and /version.

While doing so, I also made the following other improvements:

• Reduce number of implicitly and force unwrapped optionals by using non-optional conversion between String <-> Data as well as #require in tests.

• Reduce code duplication by centralizing metadata serialization

  • There are more opportunities for improvements here, but that was a rather low hanging fruit

• Performance improvements:

  • Retried requests are now re-used instead of being recreated from scratch
  • Reading response bodies now uses optimized APIs of ByteBuffer etc.
  • TimeOuts are no longer serialized into headers only to be parsed again - they are now passed directly to the execution methods instead

Thanks @ffried PR looks good. Can you run swift format . --in-place --recursive at the root of the project and push the commit?

@thoven87 Sure, done!

@thoven87 Sure, done!

Thanks! I will cut a release later today.