[core] Add simple module loading

Add a way to load modules located in modules/*

core/module.py

@@ -1,9 +1,22 @@
+import importlib
+import logging
+
+log = logging.getLogger(__name__)
 
 def load(module_name):
-    pass
+    try:
+        mod = importlib.import_module('modules.{}'.format(module_name))
+    except ImportError as error:
+        log.fatal('failed to import {}: {}'.format(module_name, str(error)))
+        return Error(module_name)
+    return getattr(mod, 'Module')()
 
 class Module(object):
     def update(self):
         pass
 
+class Error(Module):
+    def __init__(self, loaded_module_name):
+        self._loaded_module_name = loaded_module_name
+
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