implement iqdb wrapper

app/logical/iqdb/download.rb

@@ -0,0 +1,21 @@
+module Iqdb
+  class Download
+    attr_reader :source, :download, :similar_posts
+
+    def initialize(source)
+      @source = source
+    end
+
+    def download_from_source
+      tempfile = Tempfile.new("iqdb-#{$PROCESS_ID}")
+      @download = Downloads::File.new(source, tempfile.path)
+      @download.download!
+    end
+
+    def find_similar
+      if Danbooru.config.iqdb_hostname_and_port
+        @similar_posts = Iqdb::Server.new(*Danbooru.config.iqdb_hostname_and_port).query(0, 3, @download.file_path)
+      end
+    end
+  end
+end