Merge pull request #17 from gt-big-data/simpler_crawler

updated crawler and writer to crawl single threaded, simple
add duplicate detection
Merge pull request #18 from gt-big-data/no_dups

No dups
Merge branch 'master' of github.com:gt-big-data/retina-crawler into no_dups

Conflicts:
	rss_feed_parser.py