imageoverlay: Change image modifiers parameters from int to double
imageoverlay: Change image modifiers parameters from int to double

Change-Id: I5911c90c8f04d824008064964e8e3946d2acbeeb

Kurento/kms-filters,shelsonjava/kms-filters,TribeMedia/kms-filters,shelsonjava/kms-filters,TribeMedia/kms-filters,TribeMedia/kms-filters,shelsonjava/kms-filters,Kurento/kms-filters,Kurento/kms-filters