Do not perform ugprade on Jessie on CI, as it timeouts

.travis.yml

@@ -5,6 +5,7 @@ script:
     - ./test 
 
 env:
+    - NOUPGRADE=true
     - DETECTED_OS=fedora:24
     - DETECTED_OS=debian:jessie
     - DETECTED_OS=ubuntu:trusty

debian/configure_fresh_system

@@ -3,7 +3,11 @@
 set -e
 
 sudo apt-get update
-sudo apt-get -y upgrade
+
+if [[ -z $NOUPGRADE ]]; then
+    sudo apt-get -y upgrade
+fi
+
 install_packages="sudo apt-get -y --fix-missing install aptitude meld whois zsh tmux atop aria2 curl pv gajim tor torsocks nodejs icedove icedove-enigmail icedove-sogo-connector gajim lm-sensors freecad python3-pip meld whois curl pv tor torsocks nodejs npm terminator gsmartcontrol python-pip mercurial redshift gtk-redshift cmake intltool gparted wine solaar glances silversearcher-ag dkms linux-kernel-headers golang keepass2 libncurses5-dev libgnome2-dev libgnomeui-dev libgtk2.0-dev libatk1.0-dev libbonoboui2-dev libcairo2-dev libx11-dev libxpm-dev libxt-dev python-dev ruby-dev git retext kdiff3"
 
 set +e