Make milestone labels in labels tab similar to that of the labels page

I realized that some of the changes for the labels page was not reflecting in the labels list in milestone page.

## Desktop
![Screen_Shot_2016-04-11_at_4.25.36_PM](/uploads/e21f3c5a9187fe32472e796171781b5d/Screen_Shot_2016-04-11_at_4.25.36_PM.png)

## Mobile
![Screen_Shot_2016-04-11_at_4.26.47_PM](/uploads/5c9f75ca0938fc30ab47c5520215f692/Screen_Shot_2016-04-11_at_4.26.47_PM.png)


See merge request !3658