Move avatars into their own components so I can add functionality like custom default avatars and onerror sources without having to add it in 13 separate places. Add the aforementioned features.

skins/base/css/molecules/MemberTile.css

@@ -31,12 +31,6 @@ limitations under the License.
     position: relative;
 }
 
-.mx_MemberTile_avatarImg {
-    z-index: 20;
-    border-radius: 20px;
-    background-color: #dbdbdb;
-}
-
 .mx_MemberTile_inviteEditing {
     display: initial ! important;
 }