add logic to only have one version of an item.  append new tags and categories to original version of an item.
Merge branch 'master' of https://github.com/ReadUpCode/readup
add logic to register an upvote for any item submitted more than once
Merge branch 'master' of https://github.com/ReadUpCode/readup
cast an upvote for the user who posted the item
Merge branch 'master' of https://github.com/ReadUpCode/readup
Merge branch 'master' of https://github.com/DougKong/readup
clean up code by making functions for adding tags and categories to an item
related tags styling done
compiled css
Merge pull request #73 from macqueen/master

related tags styling
Merge pull request #74 from BrettHoyer/master

favicon, sorting, and amazon sdk (amazon s3 changes to follow during integration)
refactored html a bit, and moved link-form show logic into a directive
removed dom manipulation from controller, moved it to a directive
removed some old console logs
started this directive to show/hide the link-form
added some categories styling
added submit button styling and styling for tags error message
latest styles
added url error handling, and disallowing adding tags that aren't in the list. also took out some old unnecessary code.