call self.init_app if Api was created with a app

Author: hellupline

flask_rest_jsonapi/api.py

@@ -26,6 +26,9 @@ def __init__(self, app=None, blueprint=None, decorators=None):
         self.resource_registry = []
         self.decorators = decorators or tuple()
 
+        if app is not None:
+            self.init_app(app, blueprint)
+
     def init_app(self, app=None, blueprint=None):
         """Update flask application with our api