implemented javascripts for approval/disapproval/unapproval from post/show page

public/javascripts/src/app/post_moderation.js

@@ -0,0 +1,50 @@
+(function() {
+  Danbooru.PostModeration = {};
+  
+  Danbooru.PostModeration.initialize_all = function() {
+    this.initialize_approve_link();
+    this.initialize_disapprove_link();
+    this.hide_or_show_approve_and_disapprove_links();
+  }
+ 
+  Danbooru.PostModeration.hide_or_show_approve_and_disapprove_links = function() {
+    if ($("meta[name=post-is-approvable]").attr("content") != "true") {
+      $("a#approve").hide();
+      $("a#disapprove").hide();
+    }
+  }
+  
+  Danbooru.PostModeration.initialize_disapprove_link = function() {
+    $("a#disapprove").click(function() {
+      $.ajax({
+        url: "/post_moderation/disapprove.js",
+        type: "put",
+        data: {
+          post_id: $("meta[name=post-id]").attr("content")
+        },
+        beforeSend: function() {
+          $("img#disapprove-wait").show();
+        }
+      });
+    });
+  }
+  
+  Danbooru.PostModeration.initialize_approve_link = function() {
+    $("a#approve").click(function() {
+      $.ajax({
+        url: "/post_moderation/approve.js",
+        type: "put",
+        data: {
+          post_id: $("meta[name=post-id]").attr("content")
+        },
+        beforeSend: function() {
+          $("img#approve-wait").show();
+        }
+      });
+    });
+  }
+})();
+
+$(document).ready(function() {
+  Danbooru.PostModeration.initialize_all();
+});