Network Adapter Refactoring and tests

There were a few confusing naming conventions, specifically with network adapter and network service, that i clarified.

There was also some circular logic in the network adapter code that needed more clarification. 
The NetAdapter interface now contains the HandleMessage method. 

Network Adapter needed tests so I went ahead and implemented some tests. 2 of the tests will fail because they depend on a TODO method from Brian, so they are currently commented out.