Form Widget validation

- reorganized jquery validation lib to include languages
- added Widget initializer class
- fixed cache method in initializer
- added widget front JS to validate and submit (ajax / post)

assets/js/widget.js

@@ -0,0 +1,88 @@
+jQuery(function($) {
+  function isSameDomain(url) {
+    var link = document.createElement('a');
+    link.href = url;
+    return (window.location.hostname === link.hostname);
+  }
+
+  // backwards compatibility for older jQuery versions
+  if($.fn.on === undefined) {
+    // mimic on() function using live()
+    $.fn.on = function(events, selector, data, handler) {
+      if(typeof(selector) === 'function') {
+        $(this.context).live(events, selector);
+      } else {
+        $(selector).live(events, data, handler);
+      }
+      return this;
+    };
+  }
+
+  $(function() {
+    // setup form validation
+    $('form.mailpoet_form').validationEngine('attach', {
+      promptPosition: (parseInt(MailPoetWidget.is_rtl, 10) === 1)
+                      ? 'centerLeft' : 'centerRight',
+      scroll: false,
+      onValidationComplete: function(form, is_form_valid) {
+        if(is_form_valid === true) {
+          // get data
+          var raw_data = $(form).serializeArray(),
+          data = {};
+
+          // clear messages
+          $(form).find('.mailpoet_message').html('');
+          // hide all validation messages
+          $(form).validationEngine('hideAll');
+
+          // format data
+          $.each(raw_data, function(index, value) {
+            if(value.name.endsWith('[]')) {
+              var value_name = value.name.substr(0, value.name.length - 2);
+              // it's an array
+              if(data[value_name] === undefined) {
+                data[value_name] = [];
+              }
+              data[value_name].push(value.value);
+            } else {
+              data[value.name] = value.value;
+            }
+          });
+
+          if(isSameDomain(MailPoetWidget.ajax_url)) {
+            $.ajax(MailPoetWidget.ajax_url+ '?action=mailpoet_form_subscribe', {
+              data: JSON.stringify(data),
+              processData: false,
+              contentType: "application/json; charset=utf-8",
+              type : 'POST',
+              dataType: 'json',
+              success:function(response) {
+                // display response
+                if(response.success === true) {
+                  if(response.page !== undefined) {
+                    window.location.href = response.page;
+                  } else if(response.message !== undefined) {
+                    // success
+                    $(form)
+                      .find('.mailpoet_message')
+                      .html('<p class="mailpoet_validate_success">'+response.message+'</p>');
+                  }
+
+                  $(form).trigger('reset');
+                } else {
+                  if(response.message !== undefined) {
+                    $(form)
+                      .find('.mailpoet_message')
+                      .html('<p class="mailpoet_validate_error">'+response.message+'</p>');
+                  }
+                }
+              }
+            });
+          } else {
+            return true;
+          }
+        }
+      }
+    });
+  });
+});