Improve timings and curves on transitions

If anyone doesn't like this, it's easy to revert, so it's going
straight to master.

h/css/common.scss

@@ -1115,6 +1115,7 @@ h3.stream {
 
 .viewsort {
   @include single-transition(top, .25s);
+  @include transition-timing-function(cubic-bezier(0, 1, .55, 1));
   width: 100%;
   text-align: center;
   position: fixed;
@@ -1123,6 +1124,7 @@ h3.stream {
   z-index: 4;
 
   &.ng-hide {
+    @include transition-timing-function(cubic-bezier(1, .55, 0, 1));
     top: 0;
     display:block!important;
     overflow: hidden;

h/css/inject.scss

@@ -432,7 +432,8 @@ $baseFontSize: 14px;
 
 @media screen and (min-width: 37.5em) {
   .annotator-frame {
-    @include single-transition(margin-left, .4s);
+    @include single-transition(margin-left, .25s);
+    @include transition-timing-function(cubic-bezier(.55, 0, .2, .8));
     width: 428px;
     margin-left: -428px;
   }