Fix build on node 0.10.x
Use an anonymous namespace for the globals

How C++ spells 'static'.
Add JS wrapper module

So we can provide more idiomatic interfaces, though many of them will be
directly exported.
Bring coding style closer to Google style

Because V8 is written that way, so we may as well match it. Also it's what I'm
used it.
Actually send to the instance selected
Expose an event interface for messages
Somewhat better error handling
Add some sort of package.json
Properly free notices

ZFreeNotice only frees the packet data attached to a ZNotice_t. The ZNotice_t
itself may as well live on the stack.
Tidy up error handling

- No error is null, not undefined.
- Don't return the a copy of the input in subscribe
- Return an error object with com_err info
Match libzephyr API names