Fixed bugs in moviedb (imdb) metadata scraper

I discovered this bug when the scraper matched some erotic movie when it found http://us.imdb.com/Title?tt0020629/ in the nfo file. This was due to two problems in the code:
-The scraper didn't allow the use of tt in the Title? syntax. I changed the regexp so it now allows those (as IMDB themselves also allow it).
-The scraper minimally matched the IMDB url (due to the usage of * instead of +) anyways resulting in an empty IMDB id and thus the moviedb curl resulted in: http://api.tmdb.org/3/movie/tt?api_key=57983e31fb435df4df77afb854740ea9&language=en ... an asian erotic movie. Fixed this by not allowing empty imdb ids in the regular expressions, they now require at least one digit.