Revert "[airplay] - merge the binary plist and xml plist pathes in airpl...

...ay (which already diverged) by using libplist for parsing in both cases - not only the binary case"

This reverts commit 392babec96915939f416efa6888e1379140ad725. Because it
was plain wrong - the text version of the airplay protocol is not even
XML.

I had a brainfart here and luckily there are still apps out there which don't use plist airplay format so this was discovered and can be fixed for helix right in time :) - confirmed by the user who noticed the regression.