Use all_col_comments when specifying a $database for getListTableColumnsSQL()

Using user_col_comments in the INNER JOIN when referencing all_tab_columns causes no results to be returned.
use platform specific datetime format for assertions
Merge pull request #396 from darkindex/DBAL-645

DBAL-645: Oracle Platform: Cannot list table columns from a different schema
Merge pull request #398 from deeky666/fix-write-test

Use platform specific datetime format for assertions in WriteTest