Merge branch 'issue_15093' into 'master'

Set tooltips for new added labels

Fixes #15093 

![Screen_Shot_2016-04-11_at_5.50.21_PM](/uploads/52d06f6ccb3ca42e7ce75b94111514c2/Screen_Shot_2016-04-11_at_5.50.21_PM.png)

See merge request !3667

app/assets/javascripts/labels_select.js.coffee

@@ -34,7 +34,7 @@ class @LabelsSelect
         labelHTMLTemplate = _.template(
             '<% _.each(labels, function(label){ %>
             <a href="<%= ["",issueURLSplit[1], issueURLSplit[2],""].join("/") %>issues?label_name=<%= label.title %>">
-            <span class="label color-label" style="background-color: <%= label.color %>;">
+            <span class="label has-tooltip color-label" title="<%= label.description %>" style="background-color: <%= label.color %>;">
             <%= label.title %>
             </span>
             </a>
@@ -165,6 +165,8 @@ class @LabelsSelect
             .html(template)
           $sidebarCollapsedValue.text(labelCount)
 
+          $('.has-tooltip', $value).tooltip(container: 'body')
+
           $value
             .find('a')
             .each((i) ->