Initial tvOS support for the SDK.

Very basic support, lots of features still missing.

Primarily missing is persistence, so don't expect things like
CurrentUser or CurrentInstallation to persist across app launches.

-----

 - Tested to work:
   - ParseObject fetch/save
   - ParseUser login/logout (not persisted)
 - Untested, likely to work:
   - Queries
   - Analytics
   - ACL/Roles
   - Config
   - Cloud
   - Relations
   - Sessions
 - Won't work
   - Installations
   - Push

Author: richardjrossiii

Parse/Internal/PlatformHooks/Unity/PlatformHooks.Unity.cs

@@ -147,6 +147,18 @@ internal static bool IsIOS {
       }
     }
 
+    /// <summary>
+    /// Returns true if the current platform is tvOS.
+    /// </summary>
+    internal static bool IsTvOS {
+      get {
+        if (settingsPath == null) {
+          throw new InvalidOperationException("Parse must be initialized before making any calls.");
+        }
+        return Application.platform == RuntimePlatform.tvOS;
+      }
+    }
+
     /// <summary>
     /// Returns true if current running platform is Windows Phone 8.
     /// </summary>
@@ -230,6 +242,9 @@ private string Load() {
           try {
             if (IsWebPlayer) {
               return PlayerPrefs.GetString("Parse.settings", null);
+            } else if (IsTvOS) {
+              Debug.Log("Running on TvOS, prefs cannot be loaded.");
+              return null;
             } else {
               using (var fs = new FileStream(settingsPath, FileMode.Open, FileAccess.Read)) {
                 var reader = new StreamReader(fs);
@@ -250,6 +265,8 @@ private void Save() {
           if (IsWebPlayer) {
             PlayerPrefs.SetString("Parse.settings", ParseClient.SerializeJsonString(data));
             PlayerPrefs.Save();
+          } else if (IsTvOS) {
+            Debug.Log("Running on TvOS, prefs cannot be saved.");
           } else {
             using (var fs = new FileStream(settingsPath, FileMode.Create, FileAccess.Write)) {
               using (var writer = new StreamWriter(fs)) {