Web crawler in Go

This is basic web crawler/scraper implementation.

Missing Features/Bugs that need fixes

• Workers are busy with delayed items. Because there is not any prioritization of NEW request with no delay. The delay proccess is blocking each worker while instead it should be each transfered in it's own goroutine and then send to priority queue
• URLQueue can only be stored in memory which in longer crawling end up unsufficient
• Better error and configuration handling would be nice
• Each request should have it's own goroutine instead of having goroutines of loops
• Some more test but only after this entire rewrite