A more elegant solution in UE4.10 for those who need it is to add a springarm to the Capsule Component of the player Character BP and attach the camera to it. The springarm has settings for Lag (to the left of the screenshot), and you can enable and define lag and separately enable and define camera rotation lag 
If you want no lag except when the player jumps, I don’t believe this will arrange that on its own without also effecting the sideways camera motion 
