refactor(slides): update slide methods and API docs

add to docs including how to use the slides and rename methods.

BREAKING CHANGE:

The Slides component has been refactored. Many methods and events were
renamed.

The following events have been renamed:

- `slideChangeStart` has been renamed `willChange`
- `change` has been renamed `didChange`

The following methods have been renamed:

`next()` has been renamed to `slideNext()`
`prev()` has been renamed to `slidePrev()`
`getIndex()` has been renamed to `getActiveIndex()`
`getNumSlides()` has been renamed to `length()`
`isAtEnd()` has been renamed to `isEnd()`
`isAtBeginning()` has been renamed to `isBeginning()`
`getSliderWidget()` has been renamed to `getSlider()`

The following method was added: `slideTo()`

All methods have been documented in the API docs:
http://ionicframework.com/docs/v2/api/components/slides/Slides/

references #5508, references ionic-team/ionic-site#458

ionic/components/slides/slides.scss

@@ -1,10 +1,5 @@
 @import "../../globals.core";
 
-ion-swipe-slides {
-  display: block;
-  width: 100%;
-  height: 100%;
-}
 
 /**
  * Swiper 3.1.2