fix: moved the datatable css to a block and fixed the images links

All the sort_*.png images are for datatables and shouldn't need to put them in public/images, the ones from the datatables.net-zf package should be used. I opened a bug on sprockets-rails: rails/sprockets-rails#503

app/assets/stylesheets/application.scss

@@ -2,7 +2,7 @@
 @import 'jquery-datetimepicker/jquery.datetimepicker';
 @import 'codemirror/lib/codemirror';
 @import 'codemirror/theme/monokai';
-@import 'datatables.net-zf/css/dataTables.foundation';
+@import 'datatables.net-zf/css/dataTables.foundation.min';
 
 // foundation related
 @import 'foundation/foundation_and_overrides';
@@ -12,6 +12,7 @@
 
 // custom forms
 @import 'blocks/base';
+@import 'blocks/datatables';
 @import 'blocks/details';
 @import 'blocks/forms';
 @import 'blocks/top_nav';
@@ -27,22 +28,3 @@
 @import 'blocks/home';
 @import 'blocks/codemirror';
 @import 'blocks/devise';
-
-.data-tables {
-  .pagination-previous a::before, .pagination-previous.disabled::before,
-  .pagination-next a::after, .pagination-next.disabled::after {
-    display: none;
-  }
-}
-
-.pagination-previous.disabled, .pagination-next.disabled {
-  a {
-    padding: 0.1875rem 0.625rem;
-    color: $medium-gray;
-    cursor: not-allowed;
-
-    &:hover {
-      background-color: transparent;
-    }
-  }
-}

app/assets/stylesheets/blocks/_datatables.scss

@@ -0,0 +1,21 @@
+.data-tables, .dataTable {
+  .pagination-previous a::before,
+  .pagination-previous.disabled::before,
+  .pagination-next a::after,
+  .pagination-next.disabled::after {
+    display: none;
+  }
+
+  .pagination-previous.disabled,
+  .pagination-next.disabled {
+    a {
+      padding: 0.1875rem 0.625rem;
+      color: $medium-gray;
+      cursor: not-allowed;
+
+      &:hover {
+        background-color: transparent;
+      }
+    }
+  }
+}

app/assets/stylesheets/blocks/_parsers.scss

@@ -80,13 +80,6 @@ ul.tagging {
   }
 }
 
-.sorting { background: image-url('/images/sort_both.png') no-repeat center right; }
-.sorting_asc { background: image-url('/images/sort_asc.png') no-repeat center right; }
-.sorting_desc { background: image-url('/images/sort_desc.png') no-repeat center right; }
-
-.sorting_asc_disabled { background: image-url('/images/sort_asc_disabled.png') no-repeat center right; }
-.sorting_desc_disabled { background: image-url('/images/sort_desc_disabled.png') no-repeat center right; }
-
 $arrowSize: 18px;
 
 .arrow {