fix NPE in iOS getInformation: could occure before in gdx-pay code, if PurchaseManager is not installed, but user calls PurchaseSystem.getInformation(...)
add robovm.xml to force link classes automatically: now we don't need to ask users to add anything into their robovm.xml (). Easier setup! :)
make PurchaseManageriOSApple work on ios 6: app crashed before, because of absence of some methods on ios6 and earlier
Fixes: