W15B-2

1. complete automatic-event-updating system - A post request will be sent to the server via url:accounts/event. If there is no new event, this request will be hooked in a while loop and query Event table every 5 secs, until one or more new events been found. According to the evnetType, the response data will be acquired by calling coresponing functions, then the data will be sent back to the client side together with the current datetime in Json format. The datetime will then be posted to server along with the next request in order to filter out-dated events.
2. add a function testEvent() for testing. A test event for the current login user will be generated immediately when a post request be sent to accounts/addevents
3. add 'test' as a eventType in database