fix(view): prevent flicker when changing tabs on android

When android changes tabs, there was slight delay between the view
becoming the cached view and the new tab becoming the active view.
Similar to how iOS's tab swap animation works, passing in opacity
prevents the leaving view from dissepearing too early, allowing
for a much smoother animation.

Author: mhartington

js/angular/service/ionicConfig.js

@@ -487,27 +487,28 @@ IonicModule
   provider.transitions.views.android = function(enteringEle, leavingEle, direction, shouldAnimate) {
     shouldAnimate = shouldAnimate && (direction == 'forward' || direction == 'back');
 
-    function setStyles(ele, x) {
+    function setStyles(ele, x, opacity) {
       var css = {};
       css[ionic.CSS.TRANSITION_DURATION] = d.shouldAnimate ? '' : 0;
       css[ionic.CSS.TRANSFORM] = 'translate3d(' + x + '%,0,0)';
+      css.opacity = opacity;
       ionic.DomUtil.cachedStyles(ele, css);
     }
 
     var d = {
       run: function(step) {
         if (direction == 'forward') {
-          setStyles(enteringEle, (1 - step) * 99); // starting at 98% prevents a flicker
-          setStyles(leavingEle, step * -100);
+          setStyles(enteringEle, (1 - step) * 99, 1); // starting at 98% prevents a flicker
+          setStyles(leavingEle, step * -100, 1);
 
         } else if (direction == 'back') {
-          setStyles(enteringEle, (1 - step) * -100);
-          setStyles(leavingEle, step * 100);
+          setStyles(enteringEle, (1 - step) * -100, 1);
+          setStyles(leavingEle, step * 100, 1);
 
         } else {
           // swap, enter, exit
-          setStyles(enteringEle, 0);
-          setStyles(leavingEle, 0);
+          setStyles(enteringEle, 0, 1);
+          setStyles(leavingEle, 0, 0);
         }
       },
       shouldAnimate: shouldAnimate