Remove param $confirmMessage.

You can set the confirm message using 'confirm' key in options.
Remove $confirmMessage param.

Confirmation message can be set using 'confirm' key in options.
Document 'default' option.
Remove "default" option from HtmlHelper::link().

Adding js code to prevent default behavior of link by itself has little value.
Update bake templates.

Now using 'confirm' key in options for FormHelper::postLink()
instead of removed param $confirmMessage.
Merge pull request #3882 from ADmad/3.0-helper

3.0 helper