reduce .media styles to their bare minimum

Sets minimum required flex styles (including an explicit starting alignment) and removes everything else.

- no need for .media-left and .media-right, we have padding utils
- no need for a .media-heading, we have margin
- no need for .media-object, we have display utils
- no need for .media-list, we have .list-unstyled util

scss/_media.scss

@@ -1,59 +1,8 @@
 .media {
   display: flex;
+  align-items: flex-start;
 }
+
 .media-body {
   flex: 1;
 }
-.media-middle {
-  align-self: center;
-}
-.media-bottom {
-  align-self: flex-end;
-}
-
-
-//
-// Images/elements as the media anchor
-//
-
-.media-object {
-  display: block;
-
-  // Fix collapse in webkit from max-width: 100% and display: table-cell.
-  &.img-thumbnail {
-    max-width: none;
-  }
-}
-
-
-//
-// Alignment
-//
-
-.media-right {
-  padding-left: $media-alignment-padding-x;
-}
-
-.media-left {
-  padding-right: $media-alignment-padding-x;
-}
-
-
-//
-// Headings
-//
-
-.media-heading {
-  margin-top: 0;
-  margin-bottom: $media-heading-margin-bottom;
-}
-
-
-//
-// Media list variation
-//
-
-.media-list {
-  padding-left: 0;
-  list-style: none;
-}