Added missing file

datasette/plugins.py

@@ -0,0 +1,17 @@
+import importlib
+import pluggy
+from . import hookspecs
+
+default_plugins = (
+    "datasette.publish.heroku",
+    "datasette.publish.now",
+)
+
+pm = pluggy.PluginManager("datasette")
+pm.add_hookspecs(hookspecs)
+pm.load_setuptools_entrypoints("datasette")
+
+# Load default plugins
+for plugin in default_plugins:
+    mod = importlib.import_module(plugin)
+    pm.register(mod, plugin)