Fix typo

update changelog

updating to app version 8.6.0

- several API changes, they are described in the new CHANGELOG file
- reorganized some code, in particular the code that lists the installed Clarius packages was moved in its own file
- moved error handling out of the MobileApiHelper.java as much as possible to focus on demonstrating API usage
- more logging
- updated Gradle
- addressed various lint warnings from Android Studio

adding more instructions for the Quickstart App