added an option to setConfig to take a 'only_crawl_id' which would look up that node in the DOM and only crawl it and its children for emojis
fixes a bug when adding emoji content to the page dynamically :smile:, then calling emojify.run() a second time all the arrays have been emptied by the shift() method, so it can't find any new emojis
Merge pull request #7 from dylanjha/master

Enhancement and Bug Fix