Move set session timer to new session timer model
Update models regression tests

Update regression tests for classes in the models directory, including
addint test files to test RampConfigs.php and SessionTimer.php.  Neither
of these contains actual tests yet, though, because I don't know how to
test the session timer, nor how to specify different application.ini
files or different application environments when regression testing.

Introduce inheritance in table settings in a single pilot table setting
file (demoSettings/Smart/Student/StudentEnrollment.ini).