Don't assume Xulrunner is in /opt/xulrunner
Don't assume Xulrunner is in /opt/xulrunner

Instalation path for Xulrunner varies from distribution to distribution.
Don't assume it's in /opt/xulrunner, but ask bash to locate executable.

Signed-off-by: Nikola Kotur <fb2b2cd4b366d3e61feb1cea7c5b4353a88a682c@gmail.com>

mdesjardins/buzzbird,mdesjardins/buzzbird,mdesjardins/buzzbird,mdesjardins/buzzbird,mdesjardins/buzzbird