Merge branch 'fix/284-issuable-weight-in-sidebar' into 'master'

Fix Weight display in Issuables' collapsed sidebar

Fixes #284.

/cc @jschatz1 

### No weight set

![Screen_Shot_2016-02-15_at_16.02.59](/uploads/3a46684f90531fe1e319a17147272c10/Screen_Shot_2016-02-15_at_16.02.59.png)

---

### Weight set

![Screen_Shot_2016-02-15_at_16.03.18](/uploads/24accd1e795d16f4802ea1f0fe98f588/Screen_Shot_2016-02-15_at_16.03.18.png)

See merge request !184

app/views/shared/issuable/_sidebar.html.haml

@@ -99,6 +99,13 @@
       - if issuable.respond_to?(:weight)
         .block.weight
+          .sidebar-collapsed-icon
+            = icon('balance-scale')
+            %span
+              - if issuable.weight
+                = issuable.weight
+              - else
+                No
           .title
             %label Weight
             - if can?(current_user, :"admin_#{issuable.to_ability_name}", @project)