Remove jquery.blockUI.js plugin

It was only used to block the issue (but not merge request) list when
the sort was changed.

app/assets/javascripts/application.js.coffee

@@ -13,7 +13,6 @@
 #= require jquery.waitforimages
 #= require jquery.atwho
 #= require jquery.scrollTo
-#= require jquery.blockUI
 #= require jquery.turbolinks
 #= require d3
 #= require cal-heatmap

app/assets/javascripts/issues.js.coffee

@@ -15,13 +15,6 @@
           $(this).html totalIssues + 1
         else
           $(this).html totalIssues - 1
-    $("body").on "click", ".issues-other-filters .dropdown-menu a", ->
-      $('.issues-list').block(
-        message: null,
-        overlayCSS:
-          backgroundColor: '#DDD'
-          opacity: .4
-      )
 
   reload: ->
     Issues.initSelects()