Updated protocol buffers to latest from v2.5

The generated unit test files are from the latest “proto” files from
version 2.5 of the compiler.
Updated tests and test data to match v2.5

The tests have been updated to read all the messages from the v2.5
golden message file.  They produce, byte for byte the same message.
The plain text descriptions of the golden files have been added into
reference. While not as functionally complete, this project now
supports interop with 2.5.
Merge branch 'upgrade-to-latest-unittests'