gradle: v3: feature complete.

*NOTE* This branch will be rebased as fixes are applied.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: temporary build adjustments

- gradle: a script to fully exercise the gradle build
- gradle: we need an up-to-date bnd for the gradle build
- gradle: we don't want verbose mode for now

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>