make the default scaling factor a power of two
make the default scaling factor a power of two

shaih/HElib,AlexanderViand/HElib,shaih/HElib,berserkr/HElib,berserkr/HElib,AlexanderViand/HElib,shaih/HElib,berserkr/HElib,AlexanderViand/HElib