Add yandex-beta

Yandex browser beta (also named as Custo) with absolutely new UI :)

<img src="https://cloud.githubusercontent.com/assets/6201068/9814929/c30c3224-589a-11e5-8761-967360233fae.png" width="400"/>

----

* split name
* add vendor

Casks/yandex-beta.rb

@@ -0,0 +1,13 @@
+cask :v1 => 'yandex-beta' do
+  version :latest
+  sha256 :no_check
+
+  url 'https://browser.yandex.ru/download/?betacusto=1&os=mac'
+  name 'Yandex.Browser'
+  name 'Custo'
+  homepage 'https://browser.yandex.ru/beta/'
+  license :commercial
+  tags :vendor => 'Yandex'
+
+  app 'Yandex.app'
+end