STRM-12: activity stream gadget should accept currentuser parameter

STRM-12: Update JS to accept non-exist value in option box

STRM-12: Add keyword pair to resolved special input value Changes included: _ Update JS chosen library to accept non-existed value, and create new option dropdown. _ Update Java: Create resolveKeyword() to handle currentUser and future keywords .In the future, user can input a pair String-String as keyword-value to that method for auto resolved in feedFeeder.