Update Doc to correct return values of isConnected

Updating the Documentation to correct return values of `isConnected()`, `isScanning()`, `isDiscovered()` and `isInitialized()` and removing semicolon of json return statements as this is not correct here.

Would be nice to have the same signature through the whole code. Of course the return values are only boolean, but for wrapping the in promises it would be easier.

I started working on an application for a rather complex Bluetooth LE device for a university project. I already created a mock for the Bluetooth, as soon as it is finished i will add it here including unit tests which should be usable on the real thing as well.

Thanks for the work so far. I am planning to include some windows platform ideally windows8 as well, anybody working on this already? I saw chrome has an Bluetooth LE API, i will take a look at these in the coming next month.