Add Kotlin + recent Gradle example

[cthiebault]

This is a copy of aws-java-simple-http-endpoint example but migrated to Kotlin and latest Gradle version.

[pgrzesik]

Hello @cthiebault - thanks a lot for your submission. Unfortunately, I'm not familiar with Kotlin so it would be hard for me to review it.

Would anyone from the community be interested in reviewing this example?