first idea for nav transition stuff

nav.js

/**
 * For each navigation controller on scope, we can have one child control animation during transitions
 * by enabling overriding a function:
 */
 
controller('MyCtrl', function($scope, $ionicNavDelegate, $ionicAnimation)) {
  var pushAnim = $ionicAnimation({
    duration: 1,
    curve: 'ease-in-out',
    step: function(v) {
      this.context.fromEl.style[ionic.CSS.Transform] = 'translate3d(' + -v + 'px, 0,0)';
      this.context.toEl.style[ionic.CSS.Transform] = 'translate3d(' + v + 'px, 0,0)';
    }
  })
  var nav = $ionicNavDelegate($scope);
  nav.getAnimator = function(transition) {
    /**
     * getAnimator is a function that gets passed an obj like:
     * {
     *   direction: 'push', 'pop',
     *   from: angular.element?
     *   to: angular.element?
     * }
     * This lets us have different animations for push and pop, and matches
     * the new overridable transition stuff in iOS 7:
     * https://developer.apple.com/library/ios/documentation/uikit/reference/UINavigationControllerDelegate_Protocol/Reference/Reference.html#//apple_ref/occ/intfm/UINavigationControllerDelegate/navigationController:animationControllerForOperation:fromViewController:toViewController:
     */
     
     if(direction == 'push') {
       return pushAnim;
     }
     if(direction == 'pop') {
      return popAnim;
     }
    }
  };
}