The Gradle JavaFX plugin requires Oracle JDK 8u20 or better. Travis CI
currently runs something older, and does not have a roadmap for
upgrading. This commit instructs the Travis CI VM to install JDK 8u20
via `apt` prior to actually beginning the build.
See #66
- Send notifications to #bitsquare instead of #bitsquare.io
- Skip join to cut down on noise (now that -n flag has been removed)
- Only notify on failures and first success
See #86