BTLE Support

I know discover works fine, but I'm not sure about read as I don't have any good devices here.

```html
<html style="width:100%; height:100%; overflow:hidden">
<head>
<!-- You can include external scripts here like so... -->
<!--<script src="https://cdnjs.cloudflare.com/ajax/libs/zepto/1.0/zepto.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.5.2/underscore-min.js"></script>-->
</head>
<body style="width:100%; height:100%; overflow:hidden; margin:0" bgcolor="#000">
<canvas id="canvas" width="640" height="360" style="display:block"></canvas>
<script>
function server() {
    WS.log('Welcome to WearScript');
    WS.say('Welcome to WearScript');
        
    WS.sensorOn("btle", 1);
    
    WS.subscribe("btle", function(name, address) {
        WS.log(name + "@" + address);
        WS.sensorOff();
        WSRAW.bluetoothLeRead(address, function(data) {
            WS.log("got data: " + data);
        })
    })

}
function main() {
    if (WS.scriptVersion(1)) return;
    ctx = document.getElementById('canvas').getContext("2d");
    WS.serverConnect('{{WSUrl}}', server);
}
window.onload = main;
</script>
</body>
</html>
```