eztv: Cache the seasons too

Seasons do not change that often and is really slow for navigation. IMHO is
worth caching the seasons too, as it really improves navigation.
Add option to automatically ask for subtitles
Add setting to control % complete before to start playing
Wait untill 20MB (by default) are downloaded before playing

This heuristic seems to work better. Currently some videos eztv series (suits
S3E11 for example) fail to play if we don't download enough of the file before
we play it. And is not that it stalls till it downloads more, that wouldn't be
too bad. What happens is that xbmc doesn't think it is a video at all, so it
fails and stops. And when it stops, torrent2http stops too and basically you
can't see the episode.

The problem is just that we didn't download enough of the file, as can be easily
reproduced using torrent2http manually.

Using the percentage of completed pieces is not too accurate to estimate if is
enough to play it. And, when increasing the percentage of pieces downloading to
make it work on most videos, the number ended up being too big for movies (i.e.
to download a lot) making the user wait for too long before the movie started.

Using a fixed ammount of MB seems to work better in practice.

Fixes #135
Only show eztv and yify with nice (spanish) names
Simplify yify browsing and put names in spanish

This is a quick hack, a proper patch tu support internazionalization will be
submited in the future.