[TASK] fix CS/docblock in TableHelper
[TASK] fix CS/docblock in TableHelper

some minor docblock annotation fixes. switched from empty string to null
to signal optional default value for $format argument.

pocallaghan/n98-magerun,tkn98/n98-magerun,therouv/n98-magerun,pocallaghan/n98-magerun,tkn98/n98-magerun,EmPeWe/n98-magerun,pocallaghan/n98-magerun,EmPeWe/n98-magerun,tkn98/n98-magerun,therouv/n98-magerun,EmPeWe/n98-magerun