Return klass in register function

So it can be used as a decorator

@register
class MyAutoComplete:
    pass

agnocomplete/register.py

@@ -11,6 +11,7 @@ def register(klass):
     "Register a class into the agnocomplete registry."
     logger.info("registering {}".format(klass.__name__))
     AGNOCOMPLETE_REGISTRY[klass.slug] = klass
+    return klass
 
 
 def get_agnocomplete_registry():