Add option to always analyze files with anidb during post processing.

Please let me know if I sent this pull request to the wrong place.

I was running into situations where episodes were named wrong, but still in a valid format for the name processing to get a season and episode number.  In the case where the episode number didn't exist for that season, the file would just be ignored.  However when the episode number did exist then the file would incorrectly be copied over a properly named episode.

IE:
Show S02E78.mkv

instead of

Show 278.mkv

The "AniDB Always Analyze" checkbox forces _analyze_anidb to be called, and if the results are different from a previous attempt then use the results from AniDB.