Give response back to the main thread on api calls

fix #4337

couchpotato/api.py

@@ -7,6 +7,7 @@ import urllib
 
 from couchpotato.core.helpers.request import getParams
 from couchpotato.core.logger import CPLog
+from tornado.ioloop import IOLoop
 from tornado.web import RequestHandler, asynchronous
 
 
@@ -33,7 +34,7 @@ def run_async(func):
 def run_handler(route, kwargs, callback = None):
     try:
         res = api[route](**kwargs)
-        callback(res, route)
+        IOLoop.instance().add_callback(callback, res, route)
     except:
         log.error('Failed doing api request "%s": %s', (route, traceback.format_exc()))
         callback({'success': False, 'error': 'Failed returning results'}, route)