initial support for RooWifi

0. minimize changes to upstream repo
1. add command sets to encapsulate SCI, OIC500 and current OIC commands
2. when creating a Robot(), allow user to specify command set, and
whether to use pre-existing network socket rather than open a serial
port
3. invoke commands with the user-specified command set (defaults to the
current OIC command set).
4. allow user to specify a low-level send command (necessary for
RooWifi, unnecessary for other WiFi solutions)
5. fix but in demo() -- it is being passed the object, not the demo ID
6. add .gitignore to ignore node_modules
7. add roowifi.js and test2.js