libbluetooth-dev on README

[Lorenzo Delana]

applying npm install I got

/home/devel0/.node-gyp/10.15.2/include/node/v8.h: In instantiation of ‘void v8::PersistentBase<T>::SetWeak(P*, typename v8::WeakCallbackInfo<P>::Callback, v8::WeakCallbackType) [with P = Nan::ObjectWrap; T = v8::Object; typename v8::WeakCallbackInfo<P>::Callback = void (*)(const v8::WeakCallbackInfo<Nan::ObjectWrap>&)]’:
../node_modules/nan/nan_object_wrap.h:66:61:   required from here
/home/devel0/.node-gyp/10.15.2/include/node/v8.h:9502:16: warning: cast between incompatible function types from ‘v8::WeakCallbackInfo<Nan::ObjectWrap>::Callback’ {aka ‘void (*)(const v8::WeakCallbackInfo<Nan::ObjectWrap>&)’} to ‘Callback’ {aka ‘void (*)(const v8::WeakCallbackInfo<void>&)’} [-Wcast-function-type]
  CXX(target) Release/obj.target/BluetoothSerialPort/src/linux/DeviceINQ.o
../src/linux/DeviceINQ.cc:35:14: fatal error: bluetooth/bluetooth.h: No such file or directory
     #include <bluetooth/bluetooth.h>
              ^~~~~~~~~~~~~~~~~~~~~~~

that can be fixed through apt-get install -y libbluetooth-dev

Could useful to update README about that.

[Sebastian Hammerl]

The readme already stated "Make sure that bluetooth dev libs are installed" but I added the commandline for Ubuntu I guess?

[Lorenzo Delana]

Yes that is, thanks.

Another thing, instead I needed to make some updates to make it work, I will post a PR for that.