Add evaluation license restrictions

Author: mythz

src/ServiceStack.Text/Env.cs

@@ -10,6 +10,8 @@ public static class Env
     {
         static Env()
         {
+            LicenseUtils.AssertEvaluationLicense();
+
             string platformName = null;
 
 #if NETFX_CORE
@@ -77,4 +79,15 @@ public static string ReferenceAssembyPath
             set { referenceAssembyPath = value; }
         }
     }
+
+    public static class LicenseUtils
+    {
+        public static void AssertEvaluationLicense()
+        {
+            if (DateTime.UtcNow > new DateTime(2013, 12, 31))
+                throw new Exception("The evaluation license for this software has expired. " +
+                                    "See http://www.servicestack.net to upgrade to a valid license.");
+        }
+    }
+
 }

src/ServiceStack.Text/Json/JsonReader.Generic.cs

@@ -66,6 +66,8 @@ public static ParseStringDelegate GetParseFn()
 
 		public static object Parse(string value)
 		{
+            LicenseUtils.AssertEvaluationLicense();
+
 			if (ReadFn == null)
 			{
                 if (typeof(T).IsAbstract() || typeof(T).IsInterface())

src/ServiceStack.Text/Json/JsonWriter.Generic.cs

@@ -177,6 +177,8 @@ static JsonWriter()
 
         public static void WriteObject(TextWriter writer, object value)
         {
+            LicenseUtils.AssertEvaluationLicense();
+
 #if MONOTOUCH
 			if (writer == null) return;
 #endif