code: function addProjectToUser(user, project) {
  		return addUser(user)
  		.then(function(doc) {
  			return userProject.findOneAndUpdate({username: user}, {$addToSet: {'sharedProjects': project} }, {
  				safe: true,
  				w: 'majority'
  			}).exec();
  		});
  	}
docs: Adds project to user's shared projects.