Remove Akka-based seed node infrastructure (for now)

In favor of using the simplified app.cli.SeedNode class while we
continue to debug basic UPnP functionality.
Move bootstrap node config property keys to MessageModule
Polish whitespace
Organize imports
Rename NAME_FLAG => APP_NAME_KEY and move to AppModule
Use explicit "appName" vs. "name" property

i.e. when running the app, pass

    java -jar bitsquare.jar --appName Alice

vs.

    java -jar bitsquare.jar --name Alice