Tracking Issue for API 2.0 design phase

[avive]

Wishlist for making the 2.0 API more robust and easier to use.

• NodeService: node should descriptive critical error descriptions. e.g. NTP crash on startup and addition of numerical error code - these will enable clients to provide more useful information to users and display the node restart option only when applicable. For example, on NTP crash the message string should clearly describe the error and how to resolve it and provide a unique error code. Putting the user in control is the name of the game here...
• Transaction handling: the whole pattern to get information about transactions needs to be revamped and refactored - it is way to hard to use in Api 0.2 - there are many things we can do to simplify such as unifying all tx related methods into the TransactionService and return full information from that service regardless of the transaction state.
• Refactor health checks out from the NodeService into DebuggingService so it can be disabled by explorer and api backing node to fix the big security hole we currently have. These nodes should be started with the NodeService disabled but enable health-checks.

@lrettig @moshababo @brusherru