Buildkite integration for Kotlin project

[oguzkocer]

### Tasks
- [x] Publish java/Android library to Automattic's S3 Maven
- [x] Run unit & integration tests
- [x] Run lint

[oguzkocer]

Publish java/Android library to Automattic's S3 Maven

Addressed in #81.

[oguzkocer]

Run lint

Addressed in #83.

[oguzkocer]

Kotlin integration tests were added in #246 which completes this issue.