Add constants for HTTP Accept header to JavaScript client.
Add constants for HTTP Accept header to JavaScript client.

gk-brown/HTTP-RPC,gk-brown/WebRPC,gk-brown/WebRPC,gk-brown/HTTP-RPC,gk-brown/WebRPC,gk-brown/WebRPC,gk-brown/HTTP-RPC,gk-brown/WebRPC,gk-brown/WebRPC