IMGAPI-466: allow channel='*' for GetImage et al
IMGAPI-466: allow channel='*' for GetImage et al

numericillustration/sdc-imgapi,joyent/sdc-imgapi,joyent/sdc-imgapi,joyent/sdc-imgapi,numericillustration/sdc-imgapi,numericillustration/sdc-imgapi