activity feed styling improvements (more links and better spacing)

Also added add_user_to_project to template
added $model->exists($id) method on MapperModel
added method readListAsModels() on MapperListModel
activityDto refactor wip
fixed up readListAsModels() on MongoMapper
finished refactoring of ActivityDto and related tests
Merge branch 'master' into feature/activityfeed

Conflicts:
	src/css/sf.css
fixed reset_db.php
fixed up dto
fixed MongoDecoder DateTime problem and added test
fixed timestamp display
activity filter working
activity dto sort fix
Merge branch 'master' into feature/activityfeed