Added functionality to get all most recent uploads

Before this release, the program would only get the most recent upload. If a channel uploaded 5 videos since the program last checked, the program would've only retrieved 1. This version gets all the uploads since last checked.

There is also a bug fixed so if a channel is subscribed to (or unsubscribed from) on YouTube, you simply have to press "Stop" then "Start" on the program to refresh its internal subscriptions list. (before this release you had to completely restart the program)