Add RStudio daily build cask

The RStudio daily build is the fresher, more dangerous version of rstudio-preview

Casks/rstudio-daily.rb

@@ -0,0 +1,13 @@
+cask :v1 => 'rstudio-daily' do
+  version :latest
+  sha256 :no_check
+
+  url 'http://www.rstudio.org/download/latest/daily/desktop/mac/RStudio-latest.dmg'
+  name 'RStudio'
+  homepage 'https://www.rstudio.org/download/daily/desktop/mac/'
+  license :affero
+
+  app 'RStudio.app'
+  
+  zap :delete => '~/.rstudio-desktop'
+end