bookmarking functions
drop and drop transfers paperid to topics directive
drag and drog adds saved papers to topics
draggable object is nice and small
no duplicate adds allowed
merged conflict res, added ng-hide/show for 'no abstracts added'
updated header controller
merge upstream
changed topics directive to two-way binding
removed comments and logs
Merge pull request #78 from lxn2/saveAbstract

Save abstract