NFL-Network archive - Season 2014 added

frostyon420 reported problems with the show 'Top 100 Players'. The
problem was, that the current season could not be played.

Now I determine the current season and removed the fixed '2013'
references and check it on the current season variable.
So next season only the show_archives need to be update with the new
year and new 'CIDs'.
Added 'Hard Knocks' to NFL-Network Archive

Since NFL announced that the Hard Knocks 2014 series will be available
through Gamepass in 2014, I added the category to our repository. At the
moment no videos are available but we should be ready as soon as it will
be available.
Bugfix

I fixed the error if the current season will not be found in
show_archives!

Closes #62
Whitespace fixes
Update readme. List Top 100 Players as supported

Remove attribution, as this has been more than a 2-person effort for awhile now. :-)
Tiny language adjustments
switch strings xml to po
Check cache age

Closes #56
Add German language (XML)

Closes #59
Convert German XML to po

Closes #59
Merge remote-tracking branch 'upstream/master'