Huge pack of changes, fixes!
* Fixed a major extra-nonce bug! Extra-nonce is now correctly assigned to per-miner on creation, so that each miner works on a different set of jobs.
* Implemented IJobTracker which breaks the circular dependency between IJobManager and IShareManager.
* Implemented event handler for MinerAuthentication, basically JobManager can now instantly send the current job for the miner so it can start working immediatly.
* JobManager is now notified of new blocks and will create a new job & broadcast it once so.
* JobManager is now only responsible for creating new jobs and broadcasting them (it doesn't keep track of them any more).
* Difficulty is now assigned to per-miners.
* Moved services to Service/Vanilla and Service/Stratum namespace.
* Fixed tests.
* Renamed RPCServices.cs as Services.cs.
* Fixed share accept/reject notification message, it now correctly displays the miners current difficulty.