feat(carousel): add model binding support to slide

- Add support for binding slide model to slide

src/carousel/carousel.js

@@ -316,6 +316,7 @@ function CarouselDemoCtrl($scope) {
     },
     scope: {
       active: '=?',
+      actual: '=?',
       index: '=?'
     },
     link: function (scope, element, attrs, carouselCtrl) {

src/carousel/docs/README.md

@@ -4,6 +4,8 @@ The carousel also offers support for touchscreen devices in the form of swiping.
 
 Use a `<carousel>` element with `<slide>` elements inside it.  It will automatically cycle through the slides at a given rate, and a current-index variable will be kept in sync with the currently visible slide.
 
-Use the `no-wrap` attribute on a `<carousel>` element to control the looping of slides; setting `no-wrap` to an expression which evaluates to a truthy value will prevent looping
+Use the `no-wrap` attribute on a `<carousel>` element to control the looping of slides; setting `no-wrap` to an expression which evaluates to a truthy value will prevent looping.
 
-Use the `template-url` attribute on a `<carousel>` or `<slide>` element to specify the url of a custom template to override the default templates
+Use the `template-url` attribute on a `<carousel>` or `<slide>` element to specify the url of a custom template to override the default templates.
+
+Use the `actual` attribute on a `<slide>` element to bind the slide model (or any object of interest) onto the slide directive's `$scope`, which makes it available for customization in the carousel template.