Scheduler: Fetch the actual scheduled queue and apply it in the view

[BECATRUE]

This is a sub-issue of #181.

Feature you want to implement

After implementing the basic model/view architecture In #182, I will implement the followings:

• Fetch the actual scheduled queue from the proxy server.
• Show it in view actively.

How the feature is implemented

_ScheduleThread: QThread subclass for fetching the scheduled queue

It runs repeatly, in other words, as soon as a thread is finished, the another one is created and started. Every time the thread is finished, the view is updated to the fetched scheduled queue.