[noise] Test vector format update

[Alex]

In consultation with Rhys, the test vector format[0] has been updated.

Changes include:

* Removed semiephemerals
* Removed SSKs
* Removed the cipher/dh/hash keys
* Added a "protocol_name" field
* Re-purposed the "name" field so that it is a free-form description of
  the test
* Added introduction and other minor changes

I've generated fresh vectors[1] that take advantage of these formatting
changes as well as the changes introduced in rev32.

-- 
Alex

[0] https://github.com/noiseprotocol/noise_wiki/wiki/Test-vectors
[1] https://raw.githubusercontent.com/centromere/cacophony/master/vectors/cacophony.txt