New EventDispatcher and major refactoring.

requirements.txt

@@ -9,7 +9,7 @@ marshmallow-sqlalchemy==0.22.2
 apispec==3.3.0
 apispec-webframeworks==0.5.2
 mysqlclient==1.3.12
-redis==3.4.1
+redis==3.5.3
 mutagen==1.44.0
 validators==0.12.1
 simplejson==3.17.0