[Frontend] Themes added to Timelines

open #208
Espresso and Snow now supported; bulk of
work done except for minor cleanups, like zoom
buttons; Dragging not working currently in Timelines;

platform/commonUI/themes/snow/res/sass/_mixins.scss

@@ -1,4 +1,4 @@
-@mixin containerSubtle($bg: $colorBodyBg, $fg: $colorBodyFg) {
+@mixin containerSubtle($bg: $colorBodyBg, $fg: $colorBodyFg, $hover: false) {
 	@include containerBase($bg, $fg);
 	@include boxShdw($shdwBtns);
 }