You can use the AppIndicator support extension for gnome.
Open a browser and go to the Gnome Extensions page.
Click the “Off” button to “On” to install the extension in Gnome Shell.
Once activated, you should see the appindicator icons in your system tray.
Configuring the Appindicator support
If you have not installed Gnome Tweak Tool, install it with the command:
sudo apt-get install gnome-tweak-tool
Open up Gnome Tweak Tool and go to the “Gnome Shell Extension”. Click the Tool icon beside the extension.
In the Options section, you can configure the default position of the appindicator, whether they will appear in the top panel, message tray or hide completely. You can also change the position for individual appindicator.
All rights goes to the owner.
There is also a bug report here requesting to have it installed by default: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1477216