Eric servercomm

[ericaddison]

This PR adds a class to communicate with our backend. There is a test activity here that shows how to use it, but basically here is how it goes when you want to retrieve data from the backend:

• create a new ServerCommunicator object with a View argument
• create a ServerResponseAction object to act as a callback (what to do with the response)
• create a ServerErrorAction object if desired to handle errors
  • Set the error action with ServerCommunicator.setErrorAction()
  • A default error handler is provided that logs the error and displays a message
• call the desired service from the helper functions in ServerCommunicator
  • e.g. requestViewStreamData() in the test activity

[ericaddison]

The next thing to do after this might be to try and use GSON or Jackson (or the built-in Android library) to parse the JSON into Java objects...