fix(slidebox): refactor for performance and stability

Closes #2336. Closes #2317. Closes #2290. Closes #2228. Closes #2067.
Closes #1890. Closes #1865. Closes #1850. Closes #1755. Closes #1688.
Closes #1578. Closes #1501. Closes #1353. Closes #1342. Closes #782.
Closes #416. Closes #2288.

BREAKING CHANGE: The slideBox's API has undergone many changes.

- **`<ion-slide-box>`** attributes have changed (see
  [documentation](http://ionicframework.com/docs/api/directive/ionSlideBox)):

  * `active-slide` has changed to `selected`. Change your code from
  this:

    ```html
    <ion-slide-box active-slide="activeSlideIndex"></ion-slide-box>
    ```

    To this:

    ```html
    <ion-slide-box selected="activeSlideIndex"></ion-slide-box>
    ```

  * `does-continue` has changed to `loop`.  Change your code from this:

    ```html
    <ion-slide-box does-continue="shouldLoop"></ion-slide-box>
    ```

    To this:

    ```html
    <ion-slide-box loop="shouldLoop"></ion-slide-box>
    ```

  * `auto-play` and `slide-interval` have been merged into `auto-play`.
  Change your code from this:

    ```html
    <!-- autoPlay is on -->
    <ion-slide-box auto-play="true" slide-interval="1000">
    </ion-slide-box>
    <!-- autoPlay is off -->
    <ion-slide-box auto-play="false" slide-interval="1000">
    </ion-slide-box>
    ```

    To this:

    ```html
    <!-- autoPlay is on -->
    <ion-slide-box auto-play="1000"></ion-slide-box>
    <!-- autoPlay is off -->
    <ion-slide-box auto-play="false"></ion-slide-box>
    ```

  * `show-pager` and `pager-click` have been removed. Use
  a child `<ion-slide-pager>` element. See the [`ion-slide-pager`
  documentation](http://ionicframework.com/docs/api/directive/ionSlidePager).
  Change your code from this:

  ```html
  <!-- pager using default click action -->
  <ion-slide-box show-pager="true">
  </ion-slide-box>
  <!-- pager with custom click action -->
  <ion-slide-box show-pager="true" pager-click="doSomething(index)">
  </ion-slide-box>
  ```

  To this:

  ```html
  <ion-slide-box>
    <!-- pager using default click action -->
    <ion-slide-pager></ion-slide-pager>
  </ion-slide-box>
  <ion-slide-box>
    <!-- pager with custom click action -->
    <ion-slide-pager ng-click="doSomething(index)"></ion-slide-pager>
  </ion-slide-box>
  ```

- **`$ionicSlideBoxDelegate`** methods have changed (see
  [documentation](http://ionicframework.com/docs/api/service/$ionicSlideBoxDelegate)):

  - `update()` has been removed. slideBox updates on its own now.

  - `stop()` has been removed. See `autoPlay()` below.

  - `start()` hass been removed. See `autoPlay()` below.

  - `slide(newIndex[, speed])` has been renamed to `select(newIndex[,
    speed]);

  - `currentIndex()` has been renamed to `selected()`.

  - `slidesCount()` has been renamed to `count()`.

  - New method `$ionicSlideBoxDelegate.autoPlay()`. Change your code
    from this:

    ```js
    // stop auto sliding
    $ionicSlideBoxDelegate.stop();
    // later... start auto sliding
    $ionicSlideBoxDelegate.start();
    ```

    To this:

    ```js
    var autoPlaySpeed = 3000; //wait 3000 seconds between changing slide
    // stop auto sliding
    $ionicSlideBoxDelegate.autoPlay(false);
    // later... start auto sliding
    $ionicSlideBoxDelegate.autoPlay(autoPlaySpeed);
    ```

  - `previous()` now returns the index of the previous slide and does
    not select. Change your code from this:

    ```js
    // select previous slide
    $ionicSlideBoxDelegate.previous();
    ```

    To this:

    ```js
    // select previous slide
    $ionicSlideBoxDelegate.select( $ionicSlideBoxDelegate.previous() );
    ```
  - `next()` now returns the index of the next slide and does
    not select. Change your code from this:

    ```js
    // select next slide
    $ionicSlideBoxDelegate.next();
    ```

    To this:

    ```js
    // select next slide
    $ionicSlideBoxDelegate.select( $ionicSlideBoxDelegate.next() );
    ```