Merge pull request #740 from codalab/feature/worksheet_interface

Small Changes and hot fixes for worksheets
Merge pull request #741 from codalab/feature/worksheet_interface

Show spinner until ws fully loaded
#742 Change login redirect url to /
#743 Fix bundle metadata saving
#744 rerender mathjax after saving markup
Merge branch 'refs/heads/master' into feature/worksheet_interface