Moved logic to select which add_signup_topics view is rendered (staggered/non-staggered).
Renamed add_signup_sheet to index and index to index_signup to make it more consistent.  All actions performed by the instructor follow the Rails convention, and actions by the Student are of the form <action>_signup.
Fixed the text fixtures.  Working on sign_up_sheet_controller unit test file
Fixing sign up sheet controller test fixture
Merge remote-tracking branch 'origin/rails4' into jk