Server isolation and detailed errors

Isolated the JsonServer to server.py inside protocols/json

Added specific errors for server startup timeout and server startup
failed

Refactored errors for Core to CoreError generic and refactored
StateError to CoreStateMismatchError derived from CoreError

test/manual/core.py

@@ -0,0 +1,17 @@
+from time import sleep
+from dynalab_core import Core
+from dynalab_core.config import CoreConfig
+
+
+config = CoreConfig(port=8765)
+print(config)
+dl_core = Core(config)
+dl_core.start()
+print("started")
+
+try:
+    while True:
+        dl_core.wait(1)
+        print("waiting")
+except KeyboardInterrupt:
+    dl_core.stop()