* add / update recipes and build changes for Python 3.6.6 compatibility
* include Python 3 apt packages in travis build script
* use Python 3.6 in Travis
* Enable _blake2 and _sha3 in Python 3. Remove unnecessary files.
* change zope.interface version
* update cffi version
* display notifications on Android 8.0 Oreo and higher using required notification channels
* fix daemon background service implementation for Android Oreo