Adding acceleration scaling factor

This service takes a PlanningScene message
and applies it to the monitored scene.

Ideally it should include a `bool success` field,
but it is not possible to apply the scene and check for success
without ABI changes, so leave it out for now. To get this change
pushed to indigo.

This will be set to true in indigo,
but might return false in kinetic and upcoming
after we broke the underlying API to get that information.

add new srv ApplyPlanningScene