Decouple presentation entities from data entities

[ashleybot]

We would like to separate the data layer from presentation layer. This change would:

• Differentiate presentation entities from data entities and improve implementation of UI functionality features such as partial saves
• Potentially move the data layer into it's own separate web api with a side effect of enhancing modularity
• Add a small amount of additional complexity of mapping between data and presentation entities which could be offloaded by a 3rd party tool like Automapper