Add In progress to tvshow submenu

See http://forum.xbmc.org/showthread.php?tid=189038

I found it helpful not to have to aimlessly try to find such a nice often used node and place it in easy to access under the tvshow main menu entry.

![capture](https://f.cloud.github.com/assets/3521959/2506390/88683e46-b3a6-11e3-8f15-6c145a9602ee.PNG)

Reused label for this made note of such.

There probably is a better smarter more efficient way to implemented this. I hope it at least is right, after a few days of testing seems acceptable.

Hoping i doesn't shot down as works really well.

@ronie @jmarshallnz please review.