Updated dropdown CSS
This is a start on #3279 by updating the CSS for the dropdown menu. This doesnt include any CSS for the title bar or filter field
![Screen_Shot_2016-03-04_at_12.23.49](/uploads/6f2047ec1b72974334fa56e6895a32be/Screen_Shot_2016-03-04_at_12.23.49.png)
See merge request !3092