Add Smart Gadget com.sensirion.smartgadget

The app uses several libraries from jCenter that are all open source:

• libble: https://github.com/Sensirion/libble-android
• libsmartgadet: https://github.com/Sensirion/libble-android
• androidplot: https://github.com/halfhp/androidplot
• butterknife: https://github.com/JakeWharton/butterknife

From how I understand the documentation, this is acceptable.