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:

* exceptions with stack traces often weren't formatted properly,
  and kibana could not parse them
* celery logs were duplicated - we'd collect both the json logs and
  the human readable stdout logs.

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

tests/app/test_cloudfoundry_config.py

@@ -122,8 +122,8 @@ def test_extract_cloudfoundry_config_populates_other_vars():
     extract_cloudfoundry_config()
 
     assert os.environ['SQLALCHEMY_DATABASE_URI'] == 'postgres uri'
-    assert os.environ['LOGGING_STDOUT_JSON'] == '1'
     assert os.environ['NOTIFY_ENVIRONMENT'] == '🚀🌌'
+    assert os.environ['NOTIFY_LOG_PATH'] == '/home/vcap/logs/app.log'
 
 
 @pytest.mark.usefixtures('os_environ', 'cloudfoundry_environ')

tests/app/test_config.py

@@ -57,24 +57,3 @@ def test_load_config_if_cloudfoundry_not_available(monkeypatch, reload_config):
 def test_cloudfoundry_config_has_different_defaults():
     # these should always be set on Sandbox
     assert config.Sandbox.REDIS_ENABLED is False
-
-
-def test_logging_stdout_json_defaults_to_off(reload_config):
-    os.environ.pop('LOGGING_STDOUT_JSON', None)
-    assert config.Config.LOGGING_STDOUT_JSON is False
-
-
-def test_logging_stdout_json_sets_to_off_if_not_recognised(reload_config):
-    os.environ['LOGGING_STDOUT_JSON'] = 'foo'
-
-    importlib.reload(config)
-
-    assert config.Config.LOGGING_STDOUT_JSON is False
-
-
-def test_logging_stdout_json_sets_to_on_if_set_to_1(reload_config):
-    os.environ['LOGGING_STDOUT_JSON'] = '1'
-
-    importlib.reload(config)
-
-    assert config.Config.LOGGING_STDOUT_JSON is True