Polish and Cleanup

We have some housekeeping to do in this episode. We also want to add a little polish to the podcast detail screen so that it doesn't resemble a stock table view driven app. We also need to clean up the data model a bit in preparation for persistence, and we also want to remove the pesky html tags that show up on the podcast and episode descriptions.

This is a companion discussion topic for the original entry at https://nsscreencast.com/episodes/402-podcast-app-polish-and-cleanup