Setting for game starttime in local timezone

Provide a setting to display the game starttimes in local timezone.
Needed to import the calendar module since working with timestamps and
timezones is a bit tricky in python.
settings button in main menu

Closes Issue #77.
Tweak settings text
Bugfix - resetting items

There sneaked a bug in, when first selecting Game Pass and weeks and
then Network - Network Live. After stopping the playback, the earlier
selected games were shown.
Move weeks listing into display_seasons_weeks()
Make future week check more pythonic

While writing this simple patch, I wasted an hour debugging a problem where
datetime would throw an error /only/ after the addon had been run once...

http://forum.xbmc.org/showthread.php?tid=112916

I don't know what the real problem is, but I think it's a Python bug.
Bumping xbmc.python to 2.14 (for Gotham) did not help. :-/
Small cleanup

Remove duplicate reset (done in self.init)
Separate season and non-seasonal shows

This way Super Bowl archives (and any other future non-seasonal shows)
will display under all seasons.

Also, shows are now alphabetically sorted.
0.5.1 development release (Tom Landry Edition)
Pass arguments to WindowXMLDialog

This is almost certainly a bug (though apparently a common one among xbmc
addons). Confluence passes the args explicitly, and I figure what the
 default skin does is a good idea.
Convert game_common to a class (pigskin)

This accomplishes two things. 1) turns everything into a class, making
it easier to track information such as subscription, etc. Future work
will use this more. 2) Finally remove the last XBMC bits from
game_common.

This module can now be used completely independently of XBMC, and can be
used interactively in iPython, which will help debugging efforts
immeasurably.

Closes Issue #35
Bug fix: raise on gamepass login failure
Don't open skin after Login Failure or blackout
Rename game_common module to pigskin
Use object's subscription data
re-unify login functions
Some variables cleanup
Fix fallout from class conversion

These slipped through before I renamed the file, and it's a bit annoying
to squash these back through the rename. So here they live, in all their
unimportant, unintended glory.
Small cleanup of service_blackout
Use a descriptive variable name for the http_session