Optimize JNI to managed byte array conversion in JavaUtil

Unity provides a helper method to convert a Java array into a managed
array which is much quicker than making repeated overhead-heavy
AndroidJavaClass CallStatic calls.
Added null check for the raw object returned from GetRawObject().

If a valid raw object containing a null value is passed to
AndroidJNIHelper.ConvertFromJNIArray, it will crash.
Merge pull request #169 from playgameservices/iosfixes3

Minor fixes to get current with the iOS 3.0 SDK
Changing the sign-in process for iOS to match our more modern flow
Revert last commit -- added wrong file.

This reverts commit c93f1414504a2c12260c7247ccd0f23d37223488.
Updated sign-in progress to no longer use deprecated methods
Merge pull request #110 from seandanger/master

Optimize JNI to managed byte array conversion in JavaUtil
Merge pull request #172 from playgameservices/iosfixes

Updating the sign-in process to use non-deprecated methods. Got approval from Damien. :)
Fixing a few bugs around participant status in iOS
Merge pull request #199 from playgameservices/ios_enum_fixes

Fixing a few bugs around participant status in iOS
Adding support for silent sign-in to iOS

Adding support to allow silent sign-in on iOS, which has been missing. Also, added a second button to the smoke test app to test this, and brought back our missing sdkTag.