Simplify animation used to denote draft is saved

The original implementation felt a bit too short, went with
a much simpler animation which sticks around for 5 seconds.

5 seconds seems to be the standard and the same timing gmail use

app/assets/stylesheets/common/base/compose.scss

@@ -455,50 +455,23 @@ div.ac-wrap {
 }
 
 .save-animation {
-  transition: all 1s ease-in-out;
-  -webkit-transform: scale(0.1);
-  transform: scale(0.1);
-  -webkit-animation: transformer 1.5s forwards;
-  animation: transformer 1.5s forwards;
+  -webkit-animation: transformer 5s forwards;
+  animation: transformer 5s forwards;
 }
 
 @-webkit-keyframes transformer {
-  0% {
-    -webkit-transform: scale(0.1);
-  }
-  20% {
-    -webkit-transform: scale(1.2);
-  }
-  40% {
-    -webkit-transform: scale(1);
-    -webkit-filter: opacity(1);
-  }
-  60% {
-    -webkit-transform: scale(1);
+  90% {
     -webkit-filter: opacity(1);
   }
   100% {
-    -webkit-transform: scale(1);
     -webkit-filter: opacity(0);
   }
 }
 @keyframes transformer {
-  0% {
-    transform: scale(0.1);
-  }
-  20% {
-    transform: scale(1.2);
-  }
-  40% {
-    transform: scale(1);
-    opacity: 1;
-  }
-  60% {
-    transform: scale(1);
+  90% {
     opacity: 1;
   }
   100% {
-    transform: scale(1);
     opacity: 0;
   }
 }