I still don't see bluetooth icon under settings after updating kde from backport, there is no way for me to use my bluetooth keyboard which worked in kubuntu 14.10 Reproducible: Always
That's because Kubuntu have old Bluez 4 and only old KDE4 Bluedevil supports it. You should be able to add new device by manually running "bluedevil-wizard" eg. from terminal.
*** Bug 349694 has been marked as a duplicate of this bug. ***
Thank you David, got it working!