hdf5

Initial commit for json-vol branch.
Copied REST VOL C and headers, made name change from rest-->json, REST--JSON.
Added build info.
	modified:   src/CMakeLists.txt
	new file:   src/H5VLjson.c
	new file:   src/H5VLjson.h
	new file:   src/H5VLjson_public.h
	modified:   src/Makefile.am
	modified:   src/hdf5.h