Add multiple word sources, and add new words in current position

This changes the URLs from /0px,0px to /linkedin/0px,0px or /wikipedia/0px,0px or /amazon/0px,0px. It will initially make all words disappear, since it looks for words based on source word set now. To fix that, you'll need to run Meteor.call('setSets') from console to take all words not belonging to a set and put them in the LinkedIn set.