[Frontend] Added transitional animation to Edit mode

fixes #709
- When going from browse to edit mode, the wrapper
around the object being edited will now transition in
from its edges, and the edit controls toolbar will
animate its height;
- There is no transition applied for going from edit
to browse; to do this we'd need to mod the JS on
exiting to look for the end of an animation event;
- Tested in Chrome, Safari and Firefox;
- May not be smooth with very complex objects
like Layouts with a large number of components;
- Added transitional animations to .l-object-wrapper
and .l-edit-controls;
- New 'animTo' mixin added to _effects.scss;

platform/commonUI/general/res/sass/_effects.scss

@@ -39,15 +39,20 @@
     @include pulse($animName: pulse-subtle, $dur: 500ms, $opacity0: 0.7);
 }
 
-@mixin pulseBorder($c: red, $dur: 500ms, $iteration: infinite, $delay: 0s, $opacity0: 0, $opacity100: 1) {
-    @include keyframes(pulseBorder) {
-        0%   { border-color: rgba($c, $opacity0); }
-        100% { border-color: rgba($c, $opacity100); }
+@mixin animTo($animName, $propName, $propValStart, $propValEnd, $dur: 500ms, $delay: 0) {
+    @include keyframes($animName) {
+        from { #{propName}: $propValStart; }
+        to { #{$propName}: $propValEnd; }
     }
-    @include animation-name(pulseBorder);
-    @include animation-duration($dur);
-    @include animation-direction(alternate);
-    @include animation-iteration-count($iteration);
-    @include animation-timing-function(ease);
-    @include animation-delay($delay);
+    @include animToParams($animName, $dur: 500ms, $delay: 0)
 }
+
+@mixin animToParams($animName, $dur: 500ms, $delay: 0) {
+    @include animation-name($animName);
+    @include animation-duration($dur);
+    @include animation-delay($delay);
+    @include animation-fill-mode(both);
+    @include animation-direction(normal);
+    @include animation-iteration-count(1);
+    @include animation-timing-function(ease-in-out);
+}