Doge release

Merges in version 0.9.10 of the unity plugin.

2014-11-14 Version 0.9.10 (codename: doge)
    This release is a major rearchitecting of the plugin to use
    the Play Games C++ SDK. This allows us to re-use the same code on
    all supported platforms, reducing codesize and decreasing the
    work required to add new features. This release makes few
    developer-facing API changes, apart from those required for
    correctness reasons.

    New features:
        * Post-process build is handled by pure C# code rather than
          bash / shell scripts.
        * Implemented on top of the cross platform C++ Play Games SDK
    API Changes:
        * Conversions from int to uint where applicable:
            - TurnBasedMatch.AvailableAutomatchSlots
            - TurnBasedMatch.Variant
            - IRealTimeMultiplayerClient.CreateQuickGame
            - IRealTimeMultiplayerClient.CreateWithInvitationScreen
            - ITurnBasedMultiplayerClient.CreateQuickGame
            - ITurnBasedMultiplayerClient.CreateWithInvitationScreen
        * Removes support for cloud state on iOS (a crossplatform
          alternative is coming soon).
        * Removes cloud state encrypter (only used by iOS).
        * Real Time multiplayer calls will fail immediately when the
          current match is being left or is shutdown.
        * Turn-based multiplayer APIs now take instances of TurnBasedMatch
          rather than just match ID. This is required for correctness
          (the previous API allowed silently overwriting updated matches).