#18 Track Entity state (dirty vs. clean)

[Sean McCormack]

Right now, whenever a Save is called a sql command is
always executed. Logic should be put in place to track
the state of an Entity. If changes have occured or it
is new than send to the database. If nothing has
changed, do nothing. This can be accomplished using
some type of IsDirty functionality and flagging it
internally when a property set is called.