SOC-3371 Incorrect number of likers on an activity

Fix description: in case current user doesn't like the activity, reduce total like number by 1 if number of likers is more than 2.
SOC-4166: [IE8] User popup doesn't disappear when the mouse no longer focuses on user name

Fix description:
- Add the css class "hover" when it's hovered and hide the popup when it doesn't exist.