Python sources refactoring (#592)

airbyte-integrations/template/python-source/main_dev.py

@@ -0,0 +1,9 @@
+import sys
+
+from airbyte_protocol.entrypoint import launch
+
+from template_python_source import TemplatePythonSource
+
+if __name__ == "__main__":
+    source = TemplatePythonSource()
+    launch(source, sys.argv[1:])