Updated the 84 length signature decryption

Updated the right 84 length signature decryption 06.08.2013
Encrypted sig 87 broken again (fixes #1200)
Merge commit '7a4c6cc92f9ffec9135652a49153caffa5520c29'
Remove youtube sig tests

The signature algo changes too often for the static test to make sense.
Merge remote-tracking branch 'patrickslin/patch-4'