Making the Sql Syntax Providers public and changing a few names and bits for consistency.

Adding resolver for the syntax providers and wiring it up in the boot manager.

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

@@ -0,0 +1,21 @@
+using System;
+
+namespace Umbraco.Core.Persistence.SqlSyntax
+{
+    /// <summary>
+    /// Attribute for implementations of an ISqlSyntaxProvider
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Class)]
+    public class SqlSyntaxProviderAttribute : Attribute
+    {
+        public SqlSyntaxProviderAttribute(string providerName)
+        {
+            ProviderName = providerName;
+        }
+
+        /// <summary>
+        /// Gets or sets the ProviderName that corresponds to the sql syntax in a provider.
+        /// </summary>
+        public string ProviderName { get; set; }
+    }
+}