png files have ICC profile that makes libpng-1.6* spit a wrning

[EricDeveaud]

Hello

while testing gingr-1.3, built from source code: https://github.com/marbl/gingr/archive/v1.3.tar.gz

I have the following warning spitted out by libpng

packbuilder:~ > gingr 
libpng warning: iCCP: known incorrect sRGB profile

fix is quite easy, just use convert to remove the ICC profile for the following .png files

                html/img/logo_med.png \
                html/img/harvest.png \
                html/img/marbl.png

regards

Eric