22 ui captionhistory

- add animation layer for moving in new caption text into the caption history view in VBCaptionController
- added transitions animation between sliding up/down between camera and caption history view.

Note: to see the effects of what this is really doing, have at least 3 captions in your app and then slide up/down between camera/history views. Also, try staying on history view and watching the new captions come in as you talk.