Modified so you can dynamically add content to the page and rescan for gfycats

In my case I let users write content which is added to the page dynamically, so I just call the new gfyCollection.scan() function after adding the content.  Before this, calling gfyCollection.init() twice would try to re-run gfyObject.init() for gfycats already caught in the previous scan.  Also changed the unique var to work the way I think it was supposed to originally, although it should not affect anything.