Merge pull request #101 from openwebwork/release/2.8.1

Release/2.8.1

That deals with the last of the issues I was having.  This "hotfix" has been open long enough, I think.
Fixed bug in how the files used to keep temporary data files are created.
added option to have HTML table cells use th instead of td for accessibility purposes
Merge pull request #110 from Alex-Jordan/accessibleTables

added option to have HTML table cells use th instead of td for accessibility
Merge pull request #114 from KellyBlack/bugfix_create_temp_data_file

Bugfix create temp data file (develop)
Merge branch 'develop' of https://github.com/openwebwork/pg into reduced_credit_branch
Changed the credit terminology to scoring.