Merge pull request #3 from lazytiger/master

Add go value support to js_object
Update README for new example code. Thanks for @lazytiger.
Add the lost runtime lock to Object.Key(). Rename Object.SetValue() to SetPrivate() and add GetPrivate(). Rename Object.GoValue() and Value.GoValue() to ToGo(). The GetPrivate() only for get private object the ToGo() only for conversion purpose.
performance tuning
Make JS runtime only used in the creator thread.\
Because the SpiderMonkey use thread-local storage.\
See https://github.com/ricardoquesada/Spidermonkey/blob/master/mfbt/ThreadLocal.h\
and https://github.com/ricardoquesada/Spidermonkey/blob/abb95806397d0a3523263a1faf5b21923b35f508/js/src/vm/Runtime.cpp
Make JS runtime only used in the creator thread.
Because the SpiderMoneky use thread-local storage.
Make JS data dispose in the runtime creator thread.
See https://github.com/ricardoquesada/Spidermonkey/blob/master/mfbt/ThreadLocal.h
and https://github.com/ricardoquesada/Spidermonkey/blob/abb95806397d0a3523263a1faf5b21923b35f508/js/src/vm/Runtime.cpp
Script dispose chan not initialize.
add test
add test
add test
Change Go defined JS function and property design.
fix test
Add Runtime.Use() and benchmark.
merge