Make submit handler work for dynamically inserted forms

Fixes mathiasbynens#41. This plugin now requires jQuery 1.4.2 (since we’re using `jQuery#delegate`).

README.md

@@ -35,6 +35,7 @@ input, textarea { color: #000; }
 
 ## Notes
 
+* Requires jQuery 1.4.2+.
 * Works in all A-grade browsers, including IE6.
 * Automatically checks if the browser natively supports the HTML5 `placeholder` attribute for `input` and `textarea` elements. If this is the case, the plugin won’t do anything. If `@placeholder` is only supported for `input` elements, the plugin will leave those alone and apply to `textarea`s exclusively. (This is the case for Safari 4, Opera 11.00, and possibly other browsers.)
 * Caches the results of its two feature tests in `jQuery.fn.placeholder.input` and `jQuery.fn.placeholder.textarea`. For example, if `@placeholder` is natively supported for `input` elements, `jQuery.fn.placeholder.input` will be `true`. After loading the plugin, you can re-use these properties in your own code.

jquery.placeholder.js

@@ -1,4 +1,4 @@
-/*! http://mths.be/placeholder v1.8.6 by @mathias */
+/*! http://mths.be/placeholder v1.8.7 by @mathias */
 ;(function(window, document, $) {
 
 	var isInputSupported = 'placeholder' in document.createElement('input'),
@@ -30,7 +30,7 @@
 
 		$(function() {
 			// Look for forms
-			$('form').bind('submit.placeholder', function() {
+			$(document).delegate('form', 'submit.placeholder', function() {
 				// Clear the placeholder values so they don’t get submitted
 				var $inputs = $('.placeholder', this).each(clearPlaceholder);
 				setTimeout(function() {