Fixes that when snap-scaling is true; the value could still go to a minimum of 0 instead of 10 percent.
Fixes that when snap-scaling is true; the value could still go to a minimum of 0 instead of 10 percent.

We don't want it to go to 0 because then the user can actually loose it's mesh.

Contributes to Ultimaker/Uranium/#73
Contributes to Ultimaker/Cura/#493
contributes to #CURA-287
contributes to #CURA-235

onitake/Uranium,onitake/Uranium