web bluetooth nodes

[monteslu]

Now that the noble shim is almost ready (noble/noble#238) , we should put together input and output nodes for WebBluetooth.

Will need a config node that you specify a UUID or service name, and probably a button handle the startScanning method.

The output should be straightforward. Maybe use a button to list the services from the selected BLE device, select a service, then select a characteristic that is capable of being written to. On input it can take a payload of string or array or Buffer, and write it to the characteristic.

The input node will be on a characteristic that is capable of read or notify. If it's a notify characteristic it will only have an output connector. If its a read characteristic it will have an input that will then pass the read value along as a payload of type Buffer.

here's the icon for the nodes: http://fontawesome.io/icon/bluetooth-b/