Change improve Add Show/Add Trending Show page.

Fix white screen of death when trying to add a show that is already in library by replacing "Add Show" button with "In library".
Add show sorting options.
Add handler for when Trakt returns no results.
Fix image links when anchor child images are not found at Trakt.
Add image to be used when Trakt posters are void.
Merge pull request #119 from JackDandy/feature/ImproveAddTrendingPage

Change improve Add Show/Add Trending Show page.