Bug fix for database updates

Fix a bug in which database values could be inserted in an order that did not
match the column ordering.
Merge pull request #1 from mollison/column_fix

Bug fix for database updates
Generalized overhead model.

This adds some flexibility when you are testing new techniques with
non-standard overhead names.
Merge branch 'master' of github.com:bryanward/schedcat
Minor fix.
Refactoring.