Refactoring database creation, adding sql syntax provider to account for differences in syntax between sql, ce and mysql.

Adding MySql unit test.

src/Umbraco.Core/Persistence/SqlSyntax/SyntaxConfig.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Umbraco.Core.Persistence.SqlSyntax
+{
+    internal static class SyntaxConfig
+    {
+        private static ISqlSyntaxProvider _sqlSyntaxProvider;
+
+        public static ISqlSyntaxProvider SqlSyntaxProvider
+        {
+            get
+            {
+                if(_sqlSyntaxProvider == null)
+                {
+                    throw new ArgumentNullException("SqlSyntaxProvider",
+                                                    "You must set the singleton 'Umbraco.Core.Persistence.SqlSyntax.SyntaxConfig' to use an sql syntax provider");
+                }
+                return _sqlSyntaxProvider;
+            }
+            set { _sqlSyntaxProvider = value; }
+        }
+    }
+}