sudo apt-get install indicator-datetime evolution
sudo apt-get install xfce4-panel xfce4-indicator-plugin --no-install-recommends

mkdir -p ~/.config/autostart
cat <<EOF > ~/.config/autostart/xfce4-panel.desktop
[Desktop Entry]
Type=Application
Exec=xfce4-panel &
Hidden=false
X-MATE-Autostart-enabled=true
Name=xfce4-panel
EOF

gsettings set com.canonical.indicator.datetime time-format '24-hour'