Remove obsolete CSS for the annotator editor

We don't use this editor but our own custom editor, meaning this code
isn't used since commits 54e59a8a5 and bf20c93e9.

app/assets/stylesheets/annotator_overrides.scss

@@ -1,105 +1,11 @@
 // Overrides styles of annotator.min
 //
 
-.annotator-editor .annotator-controls,
-.annotator-filter,
-.annotator-filter .annotator-filter-navigation button {
-  background: #f3f3f3;
-  background-image: none;
-  border: 0;
-  border-radius: 0;
-  border-top: 1px solid $border;
-  box-shadow: none;
-  padding: $line-height / 2 $line-height / 4;
-}
-
 .annotator-adder {
   background-image: image-url("annotator_adder.png");
   margin-top: -52px;
 }
 
-.annotator-widget {
-  background: #fff;
-  border: 1px solid $border;
-  border-radius: 0;
-  bottom: $line-height;
-  box-shadow: 0 0 5px rgba(0, 0, 0, 0.05);
-  font-family: $body-font-family;
-  font-size: $base-font-size;
-  line-height: $line-height;
-  min-width: $line-height * 13;
-
-  p {
-    color: $text;
-    padding: $line-height / 2;
-  }
-}
-
-.annotator-item,
-.annotator-editor .annotator-item input:focus,
-.annotator-editor .annotator-item textarea:focus {
-  background: #fff;
-}
-
-.annotator-widget::after,
-.annotator-editor.annotator-invert-y .annotator-widget::after {
-  background-image: image-url("annotator_items.png");
-}
-
-.annotator-editor a,
-.annotator-filter .annotator-filter-property label {
-  padding: 0 $line-height / 4;
-}
-
-.annotator-editor a {
-  background: none;
-  background-image: none;
-  border: 0;
-  box-shadow: none;
-  color: $link;
-  font-family: $body-font-family;
-  font-size: $base-font-size;
-  font-weight: normal;
-  text-shadow: none;
-  padding: 0;
-
-  &:hover,
-  &:active,
-  &:focus {
-    background: none;
-    background-image: none;
-    color: $link-hover;
-    text-decoration: underline;
-    text-shadow: none;
-  }
-
-  &::after {
-    content: none;
-  }
-
-  &.annotator-cancel {
-    background: #f04124;
-    color: #fff;
-    padding: $line-height / 4 $line-height / 2;
-
-    &:hover {
-      background: darken(#f04124, 20);
-      text-decoration: none;
-    }
-  }
-
-  &.annotator-save {
-    background: #43ac6a;
-    color: #fff;
-    padding: $line-height / 4 $line-height / 2;
-
-    &:hover {
-      background: darken(#43ac6a, 20);
-      text-decoration: none;
-    }
-  }
-}
-
 .annotator-hl {
   cursor: pointer;
   background: rgba(255, 249, 218, 0.75);