Using correct API that gives length of uncompressed data so correct amount of memory is allocated.

Introduced grpc_byte_buffer_init instead. It's now the user's responsibility to
manage memory.

- Moves them to the root of the repo.
- Makes them pass lint (except for the release tag warning).
- Includes the script to rename time.h and string.h in the spec.
- Fixes the #includes in the wrapper files.