Add cron job for zeronet bootstrap

src/freedombone-meshweb

 
 ZERONET_INDEX=/home/$MY_USERNAME/mesh.html
 
-sleep 5
+cp /etc/crontab /tmp/crontab
+if ! grep -q "zeronetavahi" /tmp/crontab; then
+    echo "* *     * * *   $MY_USERNAME    zeronetavahi > /dev/null" >> /tmp/crontab
+fi
+sudo cp /tmp/crontab /etc/crontab
 zeronetavahi
 
 existing_zeronet=$(ps aux | grep zeronet | wc -l)