Bug 809093 - [UX VD] Settings. The list should have shorter horizontal dividers

[Bug 809093](https://bugzilla.mozilla.org/show_bug.cgi?id=809093)
Patch for v1.1.0hd

Cherry pick from : 
7bc54c21c61c2b04c62ed2db061316e68ab2a8a4
0204f163f81586c6166c2e14358acf9052dfad08