BleGattCoroutines v0.2.0

This release is compiled with Kotlin 1.2.71 and relies on the version 0.30.2
of kotlinx.coroutines.

It also relies on three Splitties
artifacts (App Context, Main Thread & Checked Lazy) of the version 2.0.0-alpha06.

Changes

• GattConnection is now an interface (was previously a class). You can still instantiate it
  with constructor-like syntax.
• Instead of suspending any pending request when a disconnection has occured, a
  ConnectionClosedException will be thrown. Note that it is a subclass of CancellationException,
  so it will cancel the coroutine without crashing your application, but you should still handle it
  properly, especially if you want to retry or recover.
• You can pass ConnectionSettings when creating a GattConnection instance. With this, you can
  change transport, physical layer (aka. PHY) and enable auto connect.
• requireXxx extension functions for GattConnection, BluetoothGattService and
  BluetoothGattCharacteristic thanks to @Miha-x64 contribution.