Added two new fields to tom_add_form_field, placeholder_text and placeholder_textarea. placeholder_text is just a text field with the label content in its placeholder. placeholder_textarea is similar but for textareas. There is also a small js hack for the IE browser.

git-svn-id: https://plugins.svn.wordpress.org/tom-m8te/trunk@798928 b8457f37-d9ea-0310-8a92-e5e31aec5664