BHV-6586: Created a generic sprite animation kind.

* Updated `enyo.Select` to include a "value" property, and `enyo.Option` to include a "selected" property.
* Added a new `enyo.Style` kind to dynamically generate style tags.
* Added a new `enyo.StylesheetSupport` mixin, which generates a stylesheet that rides along next to the control it's mixed-into.
* Added `enyo.SpriteAnimation` kind which lets you easily create animated sprite images with just a few properties.