First draft of backend independent plugins

backend/plugin/plugin.py

@@ -0,0 +1,18 @@
+from posixpath import join
+
+from genericpath import isfile
+
+from plugin.binary_plugin import BinaryPlugin
+from plugin.passive_plugin import PassivePlugin
+from plugin.python_plugin import PythonPlugin
+
+
+def get_plugin_backend(spec, plugin_directory, flags, logger):
+    if spec == None and isfile(join(plugin_directory, "main.py")):
+        return PythonPlugin(plugin_directory, "main.py", flags, logger)
+    elif spec["type"] == "python":
+        return PythonPlugin(plugin_directory, spec["file"], flags, logger)
+    elif spec["type"] == "binary":
+        return BinaryPlugin(plugin_directory, spec["file"], flags, logger)
+    else:
+        return PassivePlugin(logger)