Adding show-urls argument to display just the URLs

[koldbyte]

Added a new boolean argument --show-urls with default value false.

When set to true, it will display the URLs only and not start any downloads.

This will be very helpful when anybody wants to download through a download manager.

[coderick14]

Hey. Instead of adding the if condition inside the loop, can you just shift it to line 167 after the URL has been determined? You can just place the condition after the line

courseURL := courseBaseURL + *courseName

[koldbyte]

This will print the course URLs not the actual download links.

A better position could be just before the Line: 217 after which bars and WaitGroup has been initialised. I need to print the baseURL + paths[i] so I will have to add a loop again.