interactive autograder: log on call, more exceptions (#1729)

Also fixed an unqualified exception.
gather associated text: trim whitepace and odd chars (#1729)
Connection in own function; granular exceptions handling (#1729)
Chris exercise conversion script (#1729)

Squirreling away here for good measure.
Merge branch 'master' of github.com:Stanford-Online/class2go into sef-1729-interactive-exercises
Merge pull request #1739 from Stanford-Online/sef-1729-interactive-exercises

Small interactive exercise fixes for sprint 28 (#1729)