Mark *UsingAttributes* classes as obsolete

[hisystems]

All of the UsingAttributes classes, such as DatabaseObjectUsingAttributes, and DatabaseObjectsUsingAttributes should be deprecated and the use of attributes should be the default behavior of the base classes, such as DatabaseObject and DatabaseObjects. The use of attributes should be moved to these base classes. The modifications will mean that overriding the functions will be optional and if not overridden then the class will assume that attributes are used to define the associated object relational mapping information. Therefore, doing so will be backwards compatible because any existing code that does not use attributes will have had to override the base functions and therefore will function identically.