#26 [PHP]Modified the return value for cubrid_fetch, cubrid_fetch_row, cubrid_fetch_array and cubrid_fetch_assoc when there are no more data

[Jira Trac]

According to the documents [cubrid_fetch|http://www.php.net/manual/en/function.cubrid-fetch.php], [cubrid_fetch_row|http://www.php.net/manual/en/function.cubrid-fetch-row.php], [cubrid_fetch_array|http://www.php.net/manual/en/function.cubrid-fetch-array.php] and [cubrid_fetch_assoc|http://www.php.net/manual/en/function.cubrid-fetch-assoc.php], we shouldn't return false when there are no more data, but these functions will return false in this situation now.

In order to synchronizing with the documents, when there are no more data, we return nothing, not false.