FIX make augmentSQL API consistent for strict PHP

This references silverstripe/silverstripe-translatable#113
For that issue, we needed to have the DataQuery as the second parameter to
DataQuery's augmentSQL call.  Fortunately, DataQuery was already passing this
argument.  However, where the function was defined in DataExtension, the
argument was not present.  Thus, subclasses of DataExtension could not add the
parameter to their function signature if they were running in PHP strict mode
because PHP will complain that the signatures don't match.
Merge pull request #2042 from jthomerson/fix_augment_sql_api

FIX make augmentSQL API consistent for strict PHP