accumulator: add prototypes of service methods

accumulator.h

@@ -53,6 +53,16 @@ public:
 
 	auto wait_for(uint milliseconds) -> void;
 
+	// spawns the entropy_collector_service and pools_service threads
+	auto accumulator_service() -> int;
+
+	// a long lived thread collecting entropy
+	// listens on a unix socket, receives events
+	auto entropy_collector_service() -> int;
+
+	auto pools_service() -> int;
+
+
 	Accumulator();
 	~Accumulator() noexcept;