Add JavaFX runtime for compatibility

This also adds CrashReporter
It is doable. Check out the example setup with Artifactory in the main project where credentials get added for write-access only if they're known (running in Jenkins or with a local gradle.properties), otherwise it will just continue in read-only mode:

https://github.com/MovingBlocks/Terasology/blob/develop/config/gradle/artifactory.gradle

Just need to do something similar with the signing tasks - only trigger if involved files/props are known and present :)