chroma: Delete downloaded images after use them
chroma: Delete downloaded images after use them

Change-Id: I03208ec8685f160cae827bb84fd72319392e4ffe

TribeMedia/kms-elements,TribeMedia/kms-elements,shelsonjava/kms-elements,shelsonjava/kms-elements,Kurento/kms-elements,TribeMedia/kms-elements,Kurento/kms-elements,shelsonjava/kms-elements,Kurento/kms-elements