Skip albums flag and redditdownload.py improvements

[ghost]

Hey I saw issue #17 requesting an argument to skip album downloads so I thought I would implement that, while doing so I also added a couple more things I thought would improve the script. Here is what I did:

• Added -skipAlbums flag to skip all albums(obviously).
• Change from checking for only 'imgur.com/a/' in urls to also checking for 'imgur.com/gallery' so they can now be scraped too.
• Check if url is to a reddit comments page and if so move on to next url instead of attemping to scrape and inevitably failing.

I thought they would all be usefull but only add the ones you want if you think otherwise.