integrate ugoiras into zip+webm+preview

app/logical/pixiv_web_agent.rb

@@ -0,0 +1,24 @@
+class PixivWebAgent
+  def self.build
+    mech = Mechanize.new
+
+    phpsessid = Cache.get("pixiv-phpsessid")
+    if phpsessid
+      cookie = Mechanize::Cookie.new("PHPSESSID", phpsessid)
+      cookie.domain = ".pixiv.net"
+      cookie.path = "/"
+      mech.cookie_jar.add(cookie)
+    else
+      mech.get("http://www.pixiv.net") do |page|
+        page.form_with(:action => "/login.php") do |form|
+          form['pixiv_id'] = Danbooru.config.pixiv_login
+          form['pass'] = Danbooru.config.pixiv_password
+        end.click_button
+      end
+      phpsessid = mech.cookie_jar.cookies.select{|c| c.name == "PHPSESSID"}.first
+      Cache.put("pixiv-phpsessid", phpsessid.value, 1.month) if phpsessid
+    end
+
+    mech
+  end
+end