Switch to using python xmlrpclib to check answers, include psvn when checking.

This should be significantly faster and actually correct for problems
which use the psvn for random seeding.
Fix hint editor on problem part page.
Misc provisioning stuff.
Misc cleanup.
Committing misc changes to student_sim.py
Remove parsing log from git.
Ignore changes to parselog.txt
Log a better error message when the variables table is not populated.