Format date columns when exporting

[mgallegos]

The following options will be added in the 'default_export_buttons_options':

• srcDateFormat: source (database) date format (default value: Y-m-d)
• newDateFormat: new date format (default value: m/d/Y)

Both options should be valid php date format.

These options can be override on any grid using the method:

setExportButtonsOption($option, $value)

If the the model options srcformat and newformat are set, these will replace (only on that column) the default options:

->addColumn(array('label' => 'date', 'index' => 'start_date', 'formatter' => 'date', 'formatoptions' => array('srcformat' => 'Y-m-d H:i:s', 'newformat' => 'd/m/Y h:i a')))