Added user/progress/watched and user/progress/collected endpoints including optional title, sort order and extended parameters.

Added a SortType enumeration for the ordering of progress results.
Added a TvShowProgress entity.
Added basic tests for the new progress endpoints for "normal" and "full" information.

Added a type adapter for TvShowProgress.NextEpisode deserialization due to api using json primitive false when there is no episode, and a json object when there is.
Updated the walking dead runtime test case to 45 minutes instead of 60 (backend tvdb change?) in the test_summary method in ShowServiceTest which was previously failing the test.
Removed static inner class Show from TvShowProgress and replaced usage with existing entity TvShow
Merge pull request #20 from samicemalone/dev-user-progress

Added user/progress/watched and user/progress/collected endpoints