don't capture logs directly from stdout

previously in run_app_paas.sh, we captured stdout from the app and
piped that into the log file. However, this came up with a bunch of
problems, mainly that exceptions with stack traces often weren't
formatted properly, and kibana could not parse them

instead, with the updated utils library, we can use that to log json
straight to the appropriate directory directly.

app/cloudfoundry_config.py

@@ -16,7 +16,7 @@ def extract_cloudfoundry_config():
 def set_config_env_vars(vcap_services):
     vcap_application = json.loads(os.environ.get('VCAP_APPLICATION'))
     os.environ['NOTIFY_ENVIRONMENT'] = vcap_application['space_name']
-    os.environ['LOGGING_STDOUT_JSON'] = '1'
+    os.environ['NOTIFY_LOG_PATH'] = '/home/vcap/logs/app.log'
 
     for s in vcap_services['user-provided']:
         if s['name'] == 'notify-config':