Pull in rapidjson at v1.1.0.

This patch:

 - adds README.fuchsia.md describing the repo structure and roll instructions
 - checks in rapidjson at v1.1.0 ( 2fb78f9cee01996f020d5af7592b37c5a0693b31 )
 - adds BUILD.gn

Change-Id: Ie7fa82c0a2ee1ce6b9b9fdbbfaa9c97914a8460e
39 files changed
tree: 03f4623467381d65f873c8082d615c7762e9429d
  1. BUILD.gn
  2. LICENSE
  3. README.fuchsia.md
  4. rapidjson/