Add graphicsmagick to ubuntu-trusty; resolves travis-ci/apt-package-whitelist#3765
Add graphicsmagick to ubuntu-trusty; resolves travis-ci/apt-package-whitelist#3765

Packages: graphicsmagick libgraphicsmagick3 libgraphicsmagick1-dev libgraphicsmagick++3 libgraphicsmagick++1-dev libgraphics-magick-perl graphicsmagick-imagemagick-compat graphicsmagick-libmagick-dev-compat graphicsmagick-dbg tclmagick

travis-ci/apt-package-whitelist,travis-ci/apt-package-whitelist