Refactor Reportbooru API clients.

* Combine MissedSearchService, PostViewCountService, and
  PopularSearchService into single ReportbooruService class.
* Use Danbooru::Http for these services instead of HTTParty.

test/functional/explore/posts_controller_test.rb

@@ -28,8 +28,17 @@ module Explore
         end
       end
 
+      context "#viewed" do
+        should "render" do
+          mock_post_view_rankings(Date.today, [[@post.id, 100]])
+          get viewed_explore_posts_path
+          assert_response :success
+        end
+      end
+
       context "#searches" do
         should "render" do
+          mock_post_search_rankings(Date.today, [["1girl", 100], ["original", 50]])
           get searches_explore_posts_path
           assert_response :success
         end
@@ -37,6 +46,7 @@ module Explore
 
       context "#missed_searches" do
         should "render" do
+          mock_missed_search_rankings([["1girl", 100], ["original", 50]])
           get missed_searches_explore_posts_path
           assert_response :success
         end

test/functional/posts_controller_test.rb

@@ -3,13 +3,15 @@ require "test_helper"
 class PostsControllerTest < ActionDispatch::IntegrationTest
   context "The posts controller" do
     setup do
-      PopularSearchService.stubs(:enabled?).returns(false)
-
       @user = travel_to(1.month.ago) {create(:user)}
       @post = as(@user) { create(:post, tag_string: "aaaa") }
     end
 
     context "index action" do
+      setup do
+        mock_post_search_rankings(Date.today, [["1girl", 100], ["original", 50]])
+      end
+
       should "render" do
         get posts_path
         assert_response :success

test/functional/static_controller_test.rb

@@ -16,6 +16,7 @@ class StaticControllerTest < ActionDispatch::IntegrationTest
   context "sitemap action" do
     should "work" do
       create_list(:post, 3)
+      mock_post_search_rankings(Time.zone.yesterday, [["1girl", 100.0], ["2girls", 50.0]])
       get sitemap_path, as: :xml
       assert_response :success
     end