Log message

FIXED: Google  Issue 49  - using string value "null" sends NULL to the db. For
reference - this was a requested enhancement and could be a breaking change.

	Delete	/trunk/SubSonic.Tests/Product.cs	diff
	Modify	/trunk/SubSonic.Tests/SqlQuery/SelectTests.cs	diff
	Modify	/trunk/SubSonic.Tests/SubSonic.Tests.csproj	diff
	Modify	/trunk/SubSonic/ActiveRecord/ActiveHelper.cs	diff
	Modify	/trunk/SubSonic/DataProviders/SQLiteDataProvider.cs	diff
	Modify	/trunk/SubSonic/DataProviders/SqlDataProvider.cs	diff