[2.3] GRID - Adjust sort button design

From grey to blue to match rest of theme.

I guess this is up to the theme designer but I prefer the blue hue. Thoughts?

Before:
![access control lists-before](https://cloud.githubusercontent.com/assets/825106/3552181/1f1fc47a-08f3-11e4-94ef-0c3670ae2fb3.png)

After:
![access control lists-after](https://cloud.githubusercontent.com/assets/825106/3552184/26321966-08f3-11e4-98a3-ae0a43bb9904.png)
this could be the variable $white =)