The watcher can get appointments (containing only the locator) and find them in new generated blocks. Decryption and communication with the responder is still missing
Improves the dummy watcher logic. Sets a proper structure. Watcher can now check for potential matches and handle multiple appointments with the same locator (hash collisions).
Merges tx_watcher and zmq_subscriber into a single file: watcher. Watcher will handle all the watching process and container two inner classes, the watcher and the ZMQHandler
