Make sure Group PMs show in right sidebar.

If you have a lot more individual users in your realm than group
PMs in your recent history, we were squeezing out the Group PMS.
We now max out the ratio for any sub-section in the right sidebar,
as well as bumping up the min.

(imported from commit f7c44367f2a518d27406993cb6358cc96d1aae92)

static/js/ui.js

@@ -329,6 +329,7 @@ function size_blocks(blocks, usable_height) {
 
     _.each(blocks, function (block) {
         var ratio = block.real_height / sum_height;
+        ratio = confine_to_range(0.05, ratio, 0.85);
         block.max_height = confine_to_range(40, usable_height * ratio, 1.2 * block.real_height);
     });
 }