Add support for 50 customer fields (#21)

This commit raises the number of allowed custom fields for a product
 from 30 to 50.

src/Meplato.Store2.Tests/Products/UpdateTests.cs

@@ -58,7 +58,7 @@ public void TestJsonSerialization()
                     OrderUnit = "PCE",
                     CustomField12 = "37751543"
                 };
-                var expected = "{\"customField12\":\"37751543\",\"ou\":\"PCE\",\"name\":\"Produkt 1000 (NEU!)\",\"price\":2.99}";
+                var expected = "{\"customField12\":\"37751543\",\"name\":\"Produkt 1000 (NEU!)\",\"ou\":\"PCE\",\"price\":2.99}";
                 Assert.AreEqual(expected, JsonConvert.SerializeObject(update));
             }
             // attributes explicitly set to null are serialized unlike omitted ones

src/Meplato.Store2/Catalogs/Service.cs

@@ -155,8 +155,9 @@ public class Catalog
 		#region Catalog
 
 		/// <summary>
-		///     Country is the ISO-3166 alpha-2 code for the country that the
-		///     catalog is destined for (e.g. DE or US).
+		///     Country/Region is the ISO-3166 alpha-2 code for the
+		///     country/region that the catalog is destined for (e.g. DE or
+		///     US).
 		/// </summary>
 		[JsonProperty("country")]
 		public string Country { get; set; }
@@ -497,8 +498,9 @@ public class CreateCatalog
 		#region CreateCatalog
 
 		/// <summary>
-		///     Country is the ISO-3166 alpha-2 code for the country that the
-		///     catalog is destined for (e.g. DE or US).
+		///     Country/Region is the ISO-3166 alpha-2 code for the
+		///     country/region that the catalog is destined for (e.g. DE or
+		///     US).
 		/// </summary>
 		[JsonProperty("country")]
 		public string Country { get; set; }
@@ -686,8 +688,8 @@ public class Project
 		#region Project
 
 		/// <summary>
-		///     Country specifies the country code where catalogs for this
-		///     project are located.
+		///     Country/Region specifies the country/region code where catalogs
+		///     for this project are located.
 		/// </summary>
 		[JsonProperty("country")]
 		public string Country { get; set; }