1. Install Configuration Editor
You can skip to step 2 if you have Configuration Editor installed.
Press Super (Windows) key and type Add/Remove and open Add/Remove Software.
Search for gconf-editor and install it. You may need to wait a while if you are using Add/Remove Software for the first time.
2. Use Configuration Editor to change button layout
Launch Configuration Editor.
In the Configuration Editor navigate to desktop>gnome>shell>windows
Find button_layout and enter the following to add Minimize and Maximize buttons:
:minimize,maximize,close
If you want Ubuntu-like control box, enter the following instead:
close,minimize,maximize:
3. Log out and log back in
The changes are not instant. You need to log out and log back in to see the changes.
Hope this helps.