logger - Flask logging interface

Logger implementation. IMPORTANT:

In the format of the output two custom fields are added: * ip: the ip address of the sender * req: what kind of request is processed * path: the page required Every message logged must be submitted with the keyword `extra = {“ip”: request.remote_addr,

“method”: request.method, “path”: request.path}`

extra is created by cureweb.before_after:before and set into the g object

fplaneserver.flask.logger.set_logger(app)

Create and add the logging handlers to the default flask logger. Also deal with the fall-back logger