1.4.0 Updated to the new NPO Back-End

As of the 1st of March the NPO has changed (some of) the video streaming back-end services which broke the video streaming in the app (issue #19 ).

@technimad had a great idea to add a gradient to the tips images to improve the readability of the labels (pull request #20). Although his solution (adding a gradient image view above the tip image) did not make it into this release (which applies a gradient to the tip image directly to work properly with the tvOS focus engine behaviour), thanks go out to @technimad for his suggestion and efforts! 🙌🏻