Add resending bar (and resend all option)

Factor out resend logic which was in the context menu into a separate
Resend file (it shouldn't be in the skin, but it also isn't really
suitable for a controller given 2 different views invoke it..)

src/skins/vector/css/organisms/RoomView.css

@@ -209,6 +209,10 @@ limitations under the License.
     font-size: 12px;
 }
 
+.mx_RoomView_resend_link {
+    cursor: pointer;
+}
+
 .mx_RoomView_typingBar {
     margin-top: 10px;
     margin-left: 54px;