fix(fab): center fab list for larger buttons

Author: Manduro

src/components/fab/fab.scss

@@ -128,7 +128,7 @@ ion-fab-list {
 }
 
 ion-fab-list .fab-in-list {
-  margin: 8px;
+  margin: 8px 0;
 
   width: $fab-mini-size;
   height: $fab-mini-size;
@@ -147,6 +147,11 @@ ion-fab-list .fab-in-list.show {
   transform: scale(1);
 }
 
+ion-fab-list[side=left] .fab-in-list,
+ion-fab-list[side=right] .fab-in-list {
+  margin: 0 8px;
+}
+
 ion-fab-list[side=top] {
   top: initial;
   bottom: 0;