added popover css file to imports
setting current user as a property on loginFactory so we don't have to make unnecessary requests
added active CSS styling to downvote button and changed color to match rest of color scheme
injected current user to tag controller
updated tag view to prompt non-logged in users to sign in
initial commit and basic styling for logged out popover
initial commit of popover partial
compiled css
Merge pull request #51 from macqueen/master

beginning of UI for prompting users to sign in when trying to vote