Added a field to the DataCenter table to track the design maximum in kW per data center.

Updated create.sql and the db-1.5-to-2.0 migration file.

Updated the Edit Data Center page to allow entry/modification of new field.

Updated the class DataCenter for the new field, added a MakeSafe() function, and replaced all other methods in that class to utilize MakeSafe().  Also modified all SQL calls to report errors to the error log, along with the actual SQL statement.

Updated the dc_stats page to display the design maximum kW below the Raw Wattage element.

Fixes #103