Added support for handling 400 error
Added tool tip for user name text box.
Merge remote-tracking branch 'upstream/release-6.6.3.a1' into release-6.6.3.a1

* upstream/release-6.6.3.a1:
  "1.0 www[District Library] District library link on the landing page takes users to the middle of the library page Fixed"
  Library: changed the name and enabled professional learning tab for SUSD.
  On closing the sing up popup the share and remix button doesn't works issue resolved
  Player load,share,flag events are changed.
  Char limit added in assign popup and classpage
  Implementing Library view data log event functionality has been implemented.
  implementing Libaray view data log events is in progress
Merge pull request #2028 from anilgooru/release-6.6.3.a1

Release 6.6.3.a1