Revert "Form submission to own page is more robust without the actual url. Removed it from the examples."

This reverts commit 91e87efba13199fe186eebe429da08e7e34e1973.

Empty action attributes are no longer allowed in HTML5. Also it is more secure to include the explicit URL to prevent iframe clickjacking (see http://stackoverflow.com/questions/1131781/is-it-a-good-practice-to-use-an-empty-url-for-a-html-forms-action-attribute-a)