Remove old mixins

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/main/mixins.scss

@@ -41,31 +41,6 @@
  * Prefilled mixins
  * Mixins with fixed values
  */
-@mixin bg-light-gray-gradient {
-  background: #f1f1f1;
-  background-image: -webkit-gradient(linear, 0 0, 0 30, color-stop(0.066, #f5f5f5), to(#e1e1e1));
-  background-image: -webkit-linear-gradient(#f5f5f5 6.6%, #e1e1e1);
-  background-image: -moz-linear-gradient(#f5f5f5 6.6%, #e1e1e1);
-  background-image: -ms-linear-gradient(#f5f5f5 6.6%, #e1e1e1);
-  background-image: -o-linear-gradient(#f5f5f5 6.6%, #e1e1e1);
-}
-
-@mixin bg-gray-gradient {
-  background: #eee;
-  background-image: -webkit-gradient(linear, 0 0, 0 30, color-stop(0.066, #eee), to(#dfdfdf));
-  background-image: -webkit-linear-gradient(#eee 6.6%, #dfdfdf);
-  background-image: -moz-linear-gradient(#eee 6.6%, #dfdfdf);
-  background-image: -ms-linear-gradient(#eee 6.6%, #dfdfdf);
-  background-image: -o-linear-gradient(#eee 6.6%, #dfdfdf);
-}
-
-@mixin bg-dark-gray-gradient {
-  background: #eee;
-  background-image: -webkit-linear-gradient(#e9e9e9, #d7d7d7);
-  background-image: -moz-linear-gradient(#e9e9e9, #d7d7d7);
-  background-image: -ms-linear-gradient(#e9e9e9, #d7d7d7);
-  background-image: -o-linear-gradient(#e9e9e9, #d7d7d7);
-}
 
 @mixin shade {
   @include box-shadow(0 0 3px #ddd);