Add support for complete TV show seasons, without episode numbering

[Kihltech]

The following example does not find the season, for example when a complete season is given without episode numbering in the title:

friends.s02.720p.bluray-sujaidr

In my limited testing, changing the regex in patterns.py in the following way outputs the season only: from ('season', '(s?([0-9]{1,2}))[ex]') to ('season', '(s?([0-9]{1,2}))')

But I can clearly see cases where it doesn't work and I have also for my usage added a new keyword, although there are some redundancy... (Only change is forcing s as a prefix to the season number: ('complete_season', '(s([0-9]{1,2}))')

Thanks for the great tool by the way!