Add `player.currentWidth` and `player.currentHeight`* methods for getting computed style

## Specific Changes proposed
API methods:

Component
Component.prototype.currentDimension(widthOrHeight) -> Number - It takes a string value of either width or height to return back the appropriate value
Component.prototype.currentDimensions() -> Object{width: Number, height: Number} - Returns an object with width and height properties
Component.prototype.currentHeight() -> Number - Delegates to Component#currentDimension to get back the height value
Component.prototype.currentWidth() -> Number - Delegates to Component#currentDimension to get back the width value

## Requirements Checklist
- [ X ] Feature implemented / Bug fixed
- [ X ] If necessary, more likely in a feature request than a bug fix
  - [ X ] Unit Tests updated or fixed
  - [ ] Docs/guides updated
  - [ ] Example created ([starter template on JSBin](http://jsbin.com/axedog/edit?html,output))
- [ ] Reviewed by Two Core Contributors